Advanced kink-resistant stent graft

ABSTRACT

Stent-grafts for treating thoracic aortic aneurysms and abdominal aortic aneurysms include graft portions having inflatable channels and graft extensions. The graft extensions include an undulating wire stent and porous, but substantially fluid impermeable, polytetrafluoroethylene (PTFE) graft materials.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/803,046, filed Mar. 14, 2013, which claims the benefit of U.S.Provisional Application No. 61/619,715, filed Apr. 3, 2012, the contentsof which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to implantable devices for treatingdiseased bodily lumens. More particularly, the present invention relatesto stent-grafts for treating thoracic aortic aneurysms and abdominalaortic aneurysms.

BACKGROUND

An aneurysm is a medical condition indicated generally by an expansionand weakening of the wall of an artery of a patient. Aneurysms candevelop at various sites within a patient's body. Thoracic aorticaneurysms (TAAs) or abdominal aortic aneurysms (AAAs) are manifested byan expansion and weakening of the aorta which is a serious and lifethreatening condition for which intervention is generally indicated.Existing methods of treating aneurysms include invasive surgicalprocedures with graft replacement of the affected vessel or body lumenor reinforcement of the vessel with a graft.

Surgical procedures to treat aortic aneurysms can have relatively highmorbidity and mortality rates due to the risk factors inherent tosurgical repair of this disease as well as long hospital stays andpainful recoveries. This is especially true for surgical repair of TAAs,which is generally regarded as involving higher risk and more difficultywhen compared to surgical repair of AAAs.

Due to the inherent risks and complexities of surgical repair of aorticaneurysms, endovascular repair has become a widely-used alternativetherapy, most notably in treating AAAs. Commercially availableendoprostheses for the endovascular treatment of AAAs include theAneuRx® stent graft manufactured by Medtronic, Inc. of Minneapolis,Minn., the Zenith® stent graft system sold by Cook, Inc. of Bloomington,Ind., the PowerLink® stent-graft system manufactured by Endologix, Inc.of Irvine, Calif., and the Excluder® stent graft system manufactured byW.L. Gore & Associates, Inc. of Newark, Del. A commercially availablestent graft for the treatment of TAAs is the TAGTM system manufacturedby W.L. Gore & Associates, Inc.

An endovascular prosthesis must withstand tremendous pulsatile forcesover a substantial period of time while remaining both seated and sealedwithin the vessel. In order to achieve these objectives, the device,which may comprise component parts and/or materials, must remain intact.The device must resist axial migration from the site of deployment whilebeing subjected to significant pulsatile forces, and it should havesufficient radial compliance to conform to the vessel anatomy withinwhich it is deployed so as to prevent blood leakage between the deviceand the vessel wall at both its proximal, or cephalic, end as well as atits distal, or caudal end or ends (where the net force may beretrograde). Such a device should conform to the morphology of thetreated vessel, without kinking or twisting, over the life of thepatient.

SUMMARY OF THE INVENTION

The present invention is directed to kink-resistant endovasculardevices, in particular endovascular stent-grafts. The endovasculardevices of the present invention are use, but not limited to, fortreating, thoracic aortic aneurysms and abdominal aortic aneurysms.

Some embodiments of a modular endovascular graft assembly include abifurcated main graft member formed from a supple graft material havinga main fluid flow lumen therein. The main graft member may also includean ipsilateral leg with an ipsilateral fluid flow lumen in communicationwith the main fluid flow lumen, a contralateral leg with a contralateralfluid flow lumen in communication with the main fluid flow lumen and anetwork of inflatable channels disposed on the main graft member. Thenetwork of inflatable channels may be disposed anywhere on the maingraft member including the ipsilateral and contralateral legs. Inaddition, several inflatable channels may include a separatelongitudinal channel in communication therewith, to provide additionalsupport and rigidity to the device. The network of inflatable channelsmay be configured to accept a hardenable fill or inflation material toprovide structural rigidity to the main graft member when the network ofinflatable channels is in an inflated state. The network of inflatablechannels may also include at least one inflatable cuff disposed on aproximal portion of the main graft member which is configured to sealagainst an inside surface of a patient's vessel. The fill material canalso have transient or chronic radiopacity to facilitate the placementof the modular limbs into the main graft member. A proximal anchormember may be disposed at a proximal end of the main graft member and besecured to the main graft member. The proximal anchor member may have aself-expanding proximal stent portion secured to a self-expanding distalstent portion with struts having a cross sectional area that issubstantially the same as or greater than a cross sectional area ofproximal stent portions or distal stent portions adjacent the strut. Atleast one ipsilateral graft extension having a fluid flow lumen disposedtherein may be deployed with the fluid flow lumen of the graft extensionsealed to and in fluid communication with the fluid flow lumen of theipsilateral leg of the main graft member. At least one contralateralgraft extension having a fluid flow lumen disposed therein may bedeployed with the fluid flow lumen of the graft extension sealed to andin fluid communication with the fluid flow lumen of the contralateralleg of the main graft member. For some embodiments, an outside surfaceof the graft extension may be sealed to an inside surface of thecontralateral leg of the main graft when the graft extension is in adeployed state. For some embodiments, the axial length of theipsilateral and contralateral legs may be sufficient to provide adequatesurface area contact with outer surfaces of graft extensions to providesufficient friction to hold the graft extensions in place. For someembodiments, the ipsilateral and contralateral legs may have an axiallength of at least about 2 cm. For some embodiments, the ipsilateral andcontralateral legs may have an axial length of about 2 cm to about 6 cm,more specifically, about 3 cm to about 5 cm.

Some embodiments of a modular endovascular graft assembly include abifurcated main graft member having an axial length of about 5 cm toabout 10 cm formed from a supple graft material. The main graft memberhas a main fluid flow lumen therein, an ipsilateral leg with anipsilateral fluid flow lumen in communication with the main fluid flowlumen and with an axial length of at least about 2 cm, a contralateralleg with a contralateral fluid flow lumen in communication with the mainfluid flow lumen and with an axial length of at least about 2 cm. Themain graft member also includes network of inflatable channels disposedon the main graft member, including the ipsilateral and contralaterallegs, which is configured to accept a hardenable fill material toprovide structural rigidity to the main graft member when the network ofinflatable channels are in an inflated state. Some or all of theinflatable channels may include a longitudinal inflatable channel incommunication therewith so as to provide additional support and rigidityto the device. The network of inflatable channels may also include atleast one inflatable cuff disposed on a proximal portion of the maingraft member configured to seal against an inside surface of a patient'svessel. A proximal anchor member may be disposed at a proximal end ofthe main graft member and secured to the main graft member. The proximalanchor member may have a self-expanding proximal stent portion securedto a self-expanding distal stent portion with struts. At least oneipsilateral graft extension having a fluid flow lumen disposed thereinmay have the fluid flow lumen of the graft extension sealed to and influid communication with the fluid flow lumen of the ipsilateral leg ofthe main graft member. At least one contralateral graft extension havinga fluid flow lumen disposed therein may have the fluid flow lumen of thegraft extension sealed to and in fluid communication with the fluid flowlumen of the contralateral leg of the main graft member.

Some embodiments of a method of treating a patient include providing adelivery catheter containing a radially constrained bifurcated maingraft member. The main graft member may be formed from a supple graftmaterial which has a main fluid flow lumen therein and which has anipsilateral leg with an ipsilateral fluid flow lumen in communicationwith the main fluid flow lumen and a contralateral leg with acontralateral fluid flow lumen in communication with the main fluid flowlumen. The main graft member may also include a network of inflatablechannels disposed on the main graft member. Inflatable channels of thenetwork of inflatable channels may be disposed on any portion of themain graft member including the ipsilateral and contralateral legs ofthe main graft member. The main graft member may also include a proximalanchor member which is disposed at a proximal end of the main graftmember and secured to the main graft member. The proximal anchor membermay have a self-expanding proximal stent portion secured to aself-expanding distal stent portion. Such a delivery catheter may beaxially positioned within the patient's vasculature such that the maingraft member within the delivery catheter is disposed coextensively witha vascular defect of the patient's aorta. Once this positioning has beenachieved, the proximal anchor member may be deployed so as to radiallyexpand and engage an inner surface of the patient's vasculature andanchor the proximal anchor member to the patient's aorta. Thereafter,the network of inflatable channels of the main graft member may beinflated with an inflation material so as to provide a more mechanicallyrigid structure of the main graft member. For some embodiments,inflation of the network of inflatable channels may also provide a sealbetween an outer surface of an inflatable cuff of the main graft memberand an inside surface of the patient's body lumen in contact with theinflatable cuff. For some embodiments, a hardenable fill material may beused that may assume or more solid configuration after inflation of thenetwork of inflatable channels so as to provide additional mechanicalrigidity as well as prevent leakage of the fill material. Someembodiments may also employ radiopaque inflation material to facilitatemonitoring of the fill process and subsequent engagement of graftextensions. A second delivery catheter containing a radially constrainedself-expanding contralateral graft extension may then be axiallypositioned in the contralateral leg of the main graft member with aproximal portion of the contralateral graft extension axially overlappedwith an inner fluid flow lumen of the contralateral leg of the maingraft member and a distal portion of the contralateral graft extensionaxially overlapped with a portion of the patient's contralateral iliacartery. Access to the contralateral leg of the main graft portion may beachieved by percutaneous access or femoral arteriotomy from thepatient's contralateral femoral artery with a delivery sheath or thelike. Once properly positioned, the self-expanding contralateral graftextension may be deployed by releasing the radial constraint of thesecond delivery catheter. As the contralateral graft extensionself-expands in an outward radial orientation, a seal between the innerfluid flow lumen of the contralateral graft extension, a fluid flowlumen of the contralateral leg and a fluid flow lumen of thecontralateral iliac artery may be formed. A third delivery cathetercontaining a radially constrained self-expanding ipsilateral graftextension may also be axially positioned in the ipsilateral leg of themain graft member with a proximal portion of the ipsilateral graftextension axially overlapped with an inner fluid flow lumen of theipsilateral leg of the main graft member and a distal portion of theipsilateral graft extension axially overlapped with a portion of thepatient's ipsilateral iliac artery. The self-expanding ipsilateral graftextension may then be deployed by releasing the radial constraint so asto form a seal between the inner fluid flow lumen of the ipsilateralgraft extension, a fluid flow lumen of the ipsilateral leg and a fluidflow lumen of the ipsilateral iliac artery. The ipsilateral andcontralateral graft extensions may be delivered and deployed in eitherorder.

Some embodiments of a graft extension include a fluid flow lumendisposed therein, at least one layer of permeable PTFE material, atleast one layer of semi-permeable or substantially non-permeable PTFEmaterial having no discernable node and fibril structure and aninterposed self-expanding stent formed from an elongate resilientelement helically wound with a plurality of longitudinally spaced turnsinto an open tubular configuration disposed between at least one outerlayer and at least one inner layer of PTFE material.

In some embodiments, there is provided an endovascular stent-graftincluding: a tubular stent wall having opposed first and second ends; anundulating wire having opposed first and second ends and being helicallywound into a plurality of approximate circumferential windings to definethe stent wall; the undulating wire having a plurality undulationsdefined by peaks and valleys; peaks of adjacent approximatecircumferential windings being separated by a distance with the distancebetween peaks at the first end being different from the distance betweenpeaks at the second end; the first wire end secured to a firstundulation at the first end; the second wire end secured to a secondundulation at the second end; a graft liner including first plurality oflayers of porous PTFE having no discernable node and fibril structure; agraft covering including a second plurality of layers of porous PTFEhaving no discernable node and fibril structure; and where the tubularstent wall is securably disposed between the graft covering and thegraft lining.

Other embodiments include an endovascular stent-graft including: a graftliner including first plurality of layers of porous PTFE having nodiscernable node and fibril structure; a graft covering including asecond plurality of layers of porous PTFE having no discernable node andfibril structure; and a tubular stent securably disposed between thegraft liner and the graft cover; the stent including an undulating wirehaving opposed first and second ends and being helically wound into aplurality of approximate circumferential windings to define a stentwall; the undulating wire having a plurality undulations defined bypeaks and valleys with peaks of adjacent approximate circumferentialwindings being separated by a distance; where the graft liner and thegraft covering is crimped between the peaks of adjacent approximatecircumferential windings to provide crimped graft portions.

There may be provided a method of making a crimped stent graft,including the steps of: providing a tubular stent having an innersurface and an outer surface, the stent including an undulating wirehaving opposed first and second ends and being helically wound into aplurality of approximate circumferential windings to define a stentwall; the undulating wire having a plurality undulations defined bypeaks and valleys with peaks of adjacent approximate circumferentialwindings being separated by a distance; axially stretching the tubularstent; disposing a graft liner on the inner surface of the axiallystretched tubular stent, the graft liner including first plurality oflayers of porous PTFE having no discernable node and fibril structure;disposing a graft covering on the outer surface of the axially stretchedtubular stent, the graft covering including a second plurality of layersof porous PTFE having no discernable node and fibril structure; andallowing the axially stretched tubular stent to relax, forming crimps inthe graft liner and the graft covering.

Other embodiments include a method of making a crimped stent graft,including the steps of: providing a tubular stent having an innersurface and an outer surface, the stent including an undulating wirehaving opposed first and second ends and being helically wound into aplurality of approximate circumferential windings to define a stentwall; the undulating wire having a plurality undulations defined bypeaks and valleys with peaks of adjacent approximate circumferentialwindings being separated by a distance; disposing a graft liner on theinner surface of the axially stretched tubular stent, the graft linerincluding first plurality of layers of porous PTFE having no discernablenode and fibril structure; disposing a graft covering on the outersurface of the axially stretched tubular stent, the graft coveringincluding a second plurality of layers of porous PTFE having nodiscernable node and fibril structure; placing the tubular stent, graftliner and graft cover on a shaped mandrel, the shaped mandrel includingat least one crimp shape on its outer surface; and heating and sinteringthe tubular stent, graft liner and graft cover so as to form a crimpedstent graft including at least one crimp conforming to the crimp shapeof the shaped mandrel.

Still other embodiments of the present invention include an inflatableendovascular graft including a tubular graft having opposed first andsecond open ends and having a first graft portion proximal to the firstend and a second graft portion proximal to the second end; at least onecircumferential inflatable channel disposed at the first graft portion;at least two circumferential inflatable channels disposed at the secondgraft portion; a longitudinal inflatable fill channel disposed betweenthe first end and the second end of the graft and in fluid communicationwith the at least one circumferential inflatable channel disposed at thefirst graft portion and the at least two circumferential inflatablechannels disposed at the second graft portion; a first longitudinalinflatable channel disposed along the second graft portion andtraversing the at least two circumferential inflatable channels disposedat the second graft portion, where the first longitudinal inflatablechannel is in fluid communication with the at least two circumferentialinflatable channels disposed at the second graft portion.

The present invention may further include a bifurcated inflatableendovascular graft including a tubular graft having a first end and asecond opposed bifurcated end, the second bifurcated end having a firstbranch and a second branch, the first end having a first graft portionproximal to the first end, the first branch having a first branchportion proximal to the second end, the second branch having a secondbranch portion proximal to the second end; at least one circumferentialinflatable channel disposed at the first graft portion; at least twocircumferential inflatable channels disposed at the first branchportion; at least two circumferential inflatable channels disposed atthe second branch portion; a first longitudinal inflatable fill channeldisposed between the first end and the end of the first branch portionand in fluid communication with the at least one circumferentialinflatable channel disposed at the first graft portion and the at leasttwo circumferential inflatable channels disposed at the first branchportion; a second longitudinal inflatable fill channel disposed betweenthe first end and the end of the second branch portion and in fluidcommunication with the at least one circumferential inflatable channeldisposed at the first graft portion and the at least two circumferentialinflatable channels disposed at the second branch portion; a firstlongitudinal inflatable channel dispose along the first branch portionand traversing the at least two circumferential inflatable channelsdisposed at the first branch portion, where the first longitudinalinflatable channel is in fluid communication with the at least twocircumferential inflatable channels disposed at the first branchportion; and a second longitudinal inflatable channel dispose along thesecond branch portion and traversing the at least two circumferentialinflatable channels disposed at the second branch portion, where thesecond longitudinal inflatable channel is in fluid communication withthe at least two circumferential inflatable channels disposed at thesecond branch portion.

Other embodiments include a modular endovascular graft including atubular graft having a first end and a second opposed bifurcated end,the second bifurcated end having a first branch and a second branch, thefirst end having a first graft portion proximal to the first end, thefirst branch having a first branch portion proximal to the second end,the second branch having a second branch portion proximal to the secondend; at least one circumferential inflatable channel disposed at thefirst graft portion; at least two circumferential inflatable channelsdisposed at the first branch portion; at least two circumferentialinflatable channels disposed at the second branch portion; a firstlongitudinal inflatable fill channel disposed between the first end andthe end of the first branch portion and in fluid communication with theat least one circumferential inflatable channel disposed at the firstgraft portion and the at least two circumferential inflatable channelsdisposed at the first branch portion; a second longitudinal inflatablefill channel disposed between the first end and the end of the secondbranch portion and in fluid communication with the at least onecircumferential inflatable channel disposed at the first graft portionand the at least two circumferential inflatable channels disposed at thesecond branch portion; a first longitudinal inflatable channel disposealong the first branch portion and traversing the at least twocircumferential inflatable channels disposed at the first branchportion, where the first longitudinal inflatable channel is in fluidcommunication with the at least two circumferential inflatable channelsdisposed at the first branch portion; a second longitudinal inflatablechannel dispose along the second branch portion and traversing the atleast two circumferential inflatable channels disposed at the secondbranch portion, where the second longitudinal inflatable channel is influid communication with the at least two circumferential inflatablechannels disposed at the second branch portion; a first stent-graftsecurable to the first branch portion; and a second stent-graftsecurable to the second branch portion.

The modular graft may include a first and/or second stent-graftincluding a tubular stent wall having opposed first and second ends; anundulating wire having opposed first and second ends and being helicallywound into a plurality of approximate circumferential windings to definethe stent wall; the undulating wire having a plurality undulationsdefined by peaks and valleys; peaks of adjacent approximatecircumferential windings being separated by a distance with the distancebetween peaks at the first end being different from the distance betweenpeaks at the second end; the first wire end secured to a firstundulation at the first end; the second wire end secured to a secondundulation at the second end; a graft liner including first plurality oflayers of porous PTFE having no discernable node and fibril structure; agraft covering including a second plurality of layers of porous PTFEhaving no discernable node and fibril structure; and where the tubularstent wall is securably disposed between the graft covering and thegraft lining.

These features of embodiments will become more apparent from thefollowing detailed description when taken in conjunction with theaccompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of a graft assembly useful for treating, butnot limited to, thoracic aortic aneurysms according to the presentinvention.

FIG. 2A is a perspective view of the graft assembly of FIG. 1.

FIG. 2B depicts a close up view of a proximal anchor member andconnector ring.

FIG. 3 is an elevation view of a bifurcated graft assembly useful fortreating, but not limited to, abdominal aortic aneurysms according tothe present invention.

FIG. 4 is a perspective view of the graft assembly of FIG. 3.

FIG. 5 is a close up view of one embodiment of a bifurcated region of agraft assembly according to the present invention.

FIG. 6 is an elevation view of a modular bifurcated graft assemblyuseful for treating, but not limited to, abdominal aortic aneurysmsaccording to the present invention.

FIG. 7 depicts the assembly of FIG. 6 in its implanted state.

FIG. 8 depicts one embodiment of a stent structure useful in the presentinvention.

FIGS. 9A and 9B depict various embodiments of stent structures useful inthe present invention.

FIGS. 10A through 10E depict various arrangements of helically woundstents of the present invention.

FIGS. 11A and 11B depict stent graft assemblies useful in the presentinvention.

FIG. 12 is a top cross sectional view of one embodiment of a stent graftassembly of the present invention.

FIG. 13 is a close up view of one section of a crimped stent graft ofthe present invention.

FIG. 14 is a cross sectional view of a crimped section of a crimpedstent graft useful in the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are directed generally to methods anddevices for treatment of fluid flow vessels with the body of a patient.Treatment of blood vessels is specifically indicated for someembodiments, and, more specifically, treatment of aneurysms, such as,but not limited to, thoracic aortic aneurysms and abdominal aorticaneurysms. The present invention provides various graft assemblies fortreatment of blood vessels, including modular graft assemblies,bifurcated graft assemblies, stent-graft assemblies, and combinationsthereof.

Modular graft assemblies of the present invention may include a maingraft assembly having a network of inflatable channels and a graft. Oneend the graft assembly may include a graft extension, disposed at, forexample, a distal end of the assembly. The graft assembly may bebi-furcated or non-bifurcated. The graft assembly may be formed from asupple graft material, such as ePTFE, having a main fluid flow lumentherein. The graft assembly may include porous PTFE which has nodiscernable node and fibril structure. The bifurcated graft assembly mayalso include an ipsilateral leg with an ipsilateral fluid flow lumen incommunication with the main fluid flow lumen, a contralateral leg with acontralateral fluid flow lumen in communication with the main fluid flowlumen, and a network of inflatable channels disposed on the main graftmember. For some embodiments, the main graft member may have an axiallength of about 5 cm to about 10 cm, more specifically, about 6 cm toabout 8 cm in order to span an aneurysm of a patient's aorta withoutengaging the patient's iliac arteries directly with the legs of the maingraft member.

The inflatable channels of the network of inflatable channels may bedisposed on any portion of the graft assembly including the main bodyportion, as well as the ipsilateral and contralateral legs. The networkof inflatable channels may be configured to accept a hardenable fillmaterial to provide structural rigidity to the main graft member whenthe network of inflatable channels are in an inflated state and theinflation material has been cured or hardened. Radiopaque inflationmaterial may be used to facilitate monitoring of the fill process andsubsequent engagement of graft extensions. The network of inflatablechannels may also include at least one inflatable cuff disposed on aproximal portion of the main graft member which is configured to sealagainst an inside surface of a patient's vessel, such as the aorta. Thenetwork of inflatable channels may include at least one longitudinalfill channel in communication with channels at the proximal and distalends of the device. Further, the network of inflatable channels mayinclude a longitudinal channel in communication with circumferentialchannels at one end of the device.

A proximal anchor member may be disposed at a proximal end of the maingraft member and secured to the main graft member. The proximal anchormember has a self-expanding proximal stent portion secured to aself-expanding distal stent portion with struts. Some embodiments of thestruts may have a cross sectional area that is substantially the same asor greater than a cross sectional area of proximal stent portions ordistal stent portions adjacent the strut. Such a configuration may beuseful in avoiding points of concentrated stress in the proximal anchormember or struts which couple components thereof. For some embodiments,the proximal stent of the proximal anchor member further includes aplurality of barbs having sharp tissue engaging tips that are configuredto extend in a radial outward direction in a deployed expanded state.For some embodiments, the proximal anchor member includes a 4 crownproximal stent portion and an 8 crown distal stent portion which may bemade from a superelastic alloy such as superelastic nitinol (NiTi)alloy.

For a non-bifurcated graft assembly, at least one graft extension havinga fluid flow lumen disposed therein may be deployed with the fluid flowlumen of the graft extension sealed to and in fluid communication withthe fluid flow lumen of the main graft member. The graft extension maybe disposed at the distal end of the main graft member. For a bifurcatedgraft assembly, at least one ipsilateral graft extension having a fluidflow lumen disposed therein may be deployed with the fluid flow lumen ofthe graft extension sealed to and in fluid communication with the fluidflow lumen of the ipsilateral leg of the main graft member. In addition,at least one contralateral graft extension having a fluid flow lumendisposed therein may be deployed with the fluid flow lumen of the graftextension sealed to and in fluid communication with the fluid flow lumenof the contralateral leg of the main graft member. For some embodiments,the graft extensions may include an interposed self-expanding stentdisposed between at least one outer layer and at least one inner layerof supple layers of graft material. The interposed stent disposedbetween the outer layer and inner layer of graft material may be formedfrom an elongate resilient element helically wound with a plurality oflongitudinally spaced turns into an open tubular configuration. In someembodiments, the interposed stent may have a winding, undulatingconfiguration from the proximal end to the distal end. For someembodiments, the interposed stent is may include a superelastic alloysuch as superelastic NiTi alloy. In addition, the graft material of eachgraft extension may further include at least one axial zone of lowpermeability for some embodiments.

For some embodiments, an outside surface of the graft extension may besealed to an inside surface of the main graft or a leg of the main graftwhen the graft extension is in a deployed state. For some embodiments,the axial length of the ipsilateral and contralateral legs may besufficient to provide adequate surface area contact with outer surfacesof graft extensions to provide sufficient friction to hold the graftextensions in place. For some embodiments, the ipsilateral andcontralateral legs may have an axial length of at least about 2 cm. Forsome embodiments, the ipsilateral and contralateral legs may have anaxial length of about 2 cm to about 6 cm, more specifically, about 3 cmto about 5 cm.

FIGS. 1 and 2A depict a graft assembly 10 for the treatment of ananeurysm, such as, but not limited to, a thoracic aortic aneurysm. FIGS.1 and 2A depict a graft assembly 10 that is non-bifurcated, but it willbe understood that the assembly may include a bifurcated portion. Asdepicted in FIGS. 1 and 2A, the graft assembly 10 includes a main graftmember 12 disposed between a proximal open end 14 and an opposed opendistal end 16. The main graft 12 has a wall portion 18 that bounds amain fluid flow lumen 20 disposed therein and between the opposed openends 14, 16. The graft wall portion 18 may be made from anybiocompatible, durable material, including, for example, PTFE, Dacron,and the like. Unless otherwise specifically stated, the term “PTFE” asused herein includes PTFE, porous PTFE and ePTFE, any of which may beimpermeable, semi-permeable, or permeable. Furthermore, the graftassembly 10 and any portions thereof including the main body andextensions described herein may include all PTFE, all ePTFE, or acombination thereof. In one particular embodiment, the graft wallportion 18 includes a porous PTFE material having no discernable nodeand fibril structure. Methods of formation of such materials includethose methods described in U.S. Patent Application Publication No.2006/0233990, which is incorporated by reference in its entirety herein.

With regard to graft embodiments discussed herein, such as graftassembly 10, and components thereof, the term “proximal” refers to alocation towards a patient's heart and the term “distal” refers to alocation away from the patient's heart. With regard to delivery systemcatheters and components thereof discussed herein, the term “distal”refers to a location that is disposed away from an operator who is usingthe catheter and the term “proximal” refers to a location towards theoperator.

The graft assembly 10 may include a proximal anchor member 22A, whichmay be disposed at a proximal end 14 of the main graft 12. Onerepresentative anchor system may include one as depicted in FIG. 2B. Theanchor member 22 includes a proximal stent 24, which may beself-expanding or may be balloon-expandable, that is formed from anelongate element having a generally serpentine shape with a number ofcrowns or apices at either end. As depicted in FIG. 2A, six crowns orapices are shown for stent 24A. The number of crowns or apices is notlimiting and any suitable number may be used. As depicted in FIG. 2B,eight crowns or apices may be used. A distal and/or proximal end of thestent 24 may be mechanically coupled to a connector ring 26 which isembedded in graft material, either at the proximal end 14 of the maingraft 12 or the distal end 16 of the main graft 12, or directly coupledto perforations in the proximal or distal edge region of the main graft.Embodiments of the connector ring 26 may be generally circular in shapehave regular undulations about the circumference that may besubstantially sinusoidal in shape. As depicted in FIGS. 1 and 2A, theproximal end 14 of the graft assembly 10 may include a proximal anchormember 22A. The proximal anchor member 22A may similarly include aproximal self-expanding stent 24A, which may be mechanically coupled toa proximal connector ring 26A. In addition, the assembly 10 may includea similar configuration at the distal end 16. The distal end 16 of thegraft assembly 10 may include a distal anchor member 22B. The distalanchor member 22B may similarly include a distal self-expanding stent24B, which may be mechanically coupled to a connector ring 26B. It isunderstood that the graft assembly 10 may include a proximal anchormember 22A only, a proximal anchor member 22A and a distal anchor member22B, or neither of a proximal anchor member 22A or a distal anchormember 22B. U.S. Pat. No. 7,147,660, which is incorporated by referenceherein, also includes anchor member embodiments that may be used forembodiments discussed herein.

Anchor member 22 may be configured as a self-expanding anchor memberhaving an undulating pattern and may be made from stainless steel,nickel titanium alloy or any other suitable material. The anchor member22 may be configured to be balloon expandable or self-expanding in anoutward radial direction from a radially compressed state. The proximalanchor member 22 and its components may have the same or similarfeatures, dimensions or materials to those of the stents described inU.S. Pat. No. 7,147,660, the content of which is hereby incorporated byreference in its entirety.

In a particularly desirable embodiment, a network of inflatable elementsor channels (generally depicted as reference numeral 28) is disposed onthe graft body 12. The graft assembly 10 may include at least oneproximal circumferential inflatable channel 28A and at least one distalcircumferential inflatable channel 28B. The inflatable channels 28 mayextend around the entire circumference of the graft body 12 or may onlyextend partially around the circumference of the graft body 12. The atleast one proximal circumferential inflatable channel 28A and the atleast one distal circumferential inflatable channel 28B may be incommunication with each other via a longitudinal inflatable fill channel30. The longitudinal inflatable fill channel 30 is a tubular structurewhich is designed to allow communication between the interior of theinflatable channels 28A, 28B. The inflatable channels 28A, 28B may beinflated under pressure with an inflation material (not shown) through alongitudinal inflatable fill channel 30 that has a lumen disposedtherein in fluid communication with the network of inflatable channels28. The inflation material may be retained within the network ofinflatable channels 28 by a one way-valve (not shown), disposed withinthe lumen of the longitudinal inflatable fill channel 30. The network ofinflatable channels 28 may optionally be filled with a hardenablematerial that may be configured to harden, cure or otherwise increase inviscosity or become more rigid after being injected into the channels.Hardenable inflation materials such as gels, liquids or other flowablematerials that are curable to a more solid or substantially hardenedstate may be used to provide mechanical support to the graft body 12 byvirtue of the mechanical properties of the hardened material disposedwithin the channels 28. The network of inflatable channels 28 may alsoprovide structural support to the graft body 12 when in an inflatedstate due to the stiffness of the channels created by the increasedinterior pressure within the channels even if a non-hardenable inflationmaterial, such as saline or the like, is used so long as an increasedinterior pressure can be maintained. Such an increase in stiffness orrigidity may be useful for a variety of purposes. For example, duringdeployment, inflation of the network of inflatable channels 28 may urgethe graft body 12 including the main flow channel and legs thereof toconform to a generally cylindrical configuration having open flow lumenswhich may be useful when attempting to locate and navigate the flowlumens of the graft assembly 10 with a delivery catheter, guidewire orthe like. Such location and navigation of the flow lumens of the graftassembly 10 and portions thereof may also be facilitated by the use ofradiopaque inflation materials that provide enhanced visualization underfluoroscopic imaging.

To provide further support and rigidity to the graft assembly 10, thegraft assembly 10 may include a longitudinal inflatable channel 32,disposed between and in fluid communication with at least twocircumferential inflatable channels 28. For example, the distal end 16of the graft assembly 10 may include at least two distal circumferentialinflatable channels 28B. This assembly is best seen in FIG. 2A. Thelongitudinal inflatable channel 32 is in communication with at least twodistal circumferential channels 28B, and may be in fluid communicationwith more than two distal circumferential channels 28B. Suchlongitudinal inflatable channel 32 provides further support and rigidityto the assembly 10 when inflated. The longitudinal inflatable channel 32may comprise a plurality of individual channels, each in communicationwith circumferential channels 28.

The network of inflatable channels 28 may include one or morecircumferential channels disposed completely or partially about thegraft body 12 as well as longitudinal or helical channels that mayprovide support as well as a conduit in communication with thecircumferential channels 28 that may be used for filling the network ofinflatable channels 28 with inflation material. Some embodiments mayalso employ radiopaque inflation material to facilitate monitoring ofthe fill process and subsequent engagement of graft extensions (whenused). The network of inflatable channels 28 may also include one ormore one or more enlarged circumferential channels in the form ofinflatable cuffs. The inflatable cuff (or cuffs) are disposed towardsthe end of the graft body 12, such as at the proximal end 14 or distalend 16. One example of a proximal inflatable cuff is depicted in FIG. 2Aas the circumferential inflatable channel 28A. An inflatable cuff orcuffs disposed at the ends of the body 12 may be configured to seal toan inside surface of a patient's vessel such as a patient's abdominalaorta. An inflatable cuff may be disposed on a portion of the main graft12 distal of the proximal anchor member 22A and has an outer surfacethat extends radially from a nominal outer surface of the main graft 12.The inflatable cuff may be configured to expand radially beyond anominal outer surface of the main graft 12 and provide a seal against aninside surface of a body lumen when the inflatable cuff is inflated withan inflation material to an expanded state. The axial separation of theproximal anchor member 22A and proximal inflatable cuff 28A allows forspatial separation of the primary anchoring mechanism and at least partof the sealing function which may allow the graft to be restrained orotherwise compressed to a smaller outer profile for deployment from adelivery catheter. An interior cavity of any inflatable channels 28(including one or more inflatable cuffs) is in fluid communication withthe interior cavity of the remaining network of inflatable channels 28and may have a transverse dimension or inner diameter of about 0.040inch to about 0.250 inch.

Some embodiments of main graft member 12 may include about 1 to about 8circumferential inflatable channels disposed about the graft body 12.Some embodiments of the graft body 12 may include about 1 to about 4longitudinal (or axial) inflatable fill channels 30 that may serve toconnect the circumferential inflatable channels 28. Some embodiments ofthe circumferential channels 28 may extend a full circumference of thegraft section upon which they are disposed, or they may extend onlypartially around the graft section upon which they are disposed. For thegraft body embodiment 12 shown in FIGS. 1 and 2A, the network ofinflatable channels 28 includes an inflatable cuff (28A) disposedadjacent the proximal end 14 of the main body portion of the graft body12. A longitudinal or axial channel extends substantially along thegraft body 12 in fluid communication with the circumferential channels28 and proximal inflatable cuff 28A at the proximal end of the graftbody 12. The longitudinal inflatable channel 32 extends between and isin fluid communication with three of the distal inflatable channels 28B.As the inflation material is disposed through the longitudinal fillchannel 30, each of the inflatable channels 28 (including proximalinflatable cuff 28A and distal inflatable channels 28B) is filled withinflation material. In addition, the longitudinal inflatable channel 32is filled with inflation material, resulting in a rigid and strong graftassembly 10.

Some of the inflatable channels 28 of the graft assembly 10 discussedherein may be disposed circumferentially and axially. Alternatively,such inflatable channels 28 may be disposed in spiral, helical, or otherconfigurations. Examples of channel configurations suitable forembodiments of the present invention are described further in U.S. Pat.No. 7,150,758, the entirety of which is incorporated herein byreference. All inflatable channel embodiments described herein ascircumferential, may alternatively take on any of the aforementionedalternative configurations. Other modular graft embodiments arediscussed in U.S. Patent Application Publication No. 2006/0224232, byChobotov et al. titled “Hybrid Modular Endovascular Graft”, which ishereby incorporated by reference herein in its entirety.

The network of inflatable channels 28, including an inflatable cuff andlongitudinal inflatable channel 32, may be filled during deployment ofthe graft with any suitable inflation material. As discussed above, theinflation material may be used to provide outward pressure or a rigidstructure from within the network of inflatable channels 28.Biocompatible gases, liquids, gels or the like may be used, includingcurable polymeric materials or gels, such as the polymeric biomaterialsdescribed in U.S. Patent No.7,744,912 and entitled “Biomaterials Formedby Nucleophilic Addition Reaction to Conjugated Unsaturated Groups” toHubbell et al.; U.S. Pat. No. 6,958,212 and entitled “Conjugate AdditionReactions for Controlled Delivery of Pharmaceutically Active Compounds”to Hubbell et al.; and further discussed in U.S. Pat. No. 7,147,660 andentitled “Advanced Endovascular Graft” to Chobotov, et al., each ofwhich is incorporated by reference herein in its entirety. Someembodiments may use inflation materials formed from glycidyl ether andamine materials, as discussed in U.S. Patent Application Publication No.2006/0222596 and entitled “Non-Degradable, Low-Swelling, Water SolubleRadiopaque Hydrogel Polymer” to Askari and Whirley, the contents ofwhich are incorporated herein by reference. Some inflation materialembodiments may include an in situ formed hydrogel polymer having afirst amount of diamine and a second amount of polyglycidyl etherwherein each of the amounts are present in a mammal or in a medicaldevice, such as an inflatable graft, located in a mammal in an amount toproduce an in situ formed hydrogel polymer that is biocompatible and hasa cure time after mixing of about 10 seconds to about 30 minutes andwherein the volume of said hydrogel polymer swells less than 30 percentafter curing and hydration. Some embodiments of the inflation materialmay include radiopaque material such as sodium iodide, potassium iodide,barium sulfate, Visipaque 320, Hypaque, Omnipaque 350, Hexabrix and thelike. For some inflation material embodiments, the polyglycidyl ethermay be selected from trimethylolpropane triglycidyl ether, sorbitolpolyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritolpolyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidylether, trimethylolpropane polyglycidyl ether, polyethylene glycoldiglycidyl ether, resorcinol diglycidyl ether, glycidyl ester ether ofp-hydroxy benzoic acid, neopentyl glycol diglycidyl ether,1,6-hexanediol diglycidyl ether, bisphenol A (PO )₂ diglycidyl ether,hydroquinone diglycidyl ether, bisphenol S diglycidyl ether,terephthalic acid diglycidyl ester, and mixtures thereof. For someinflation material embodiments, the diamine may be selected from(poly)alkylene glycol having amino or alkylamino termini selected fromthe group consisting of polyethylene glycol (400) diamine,di-(3-aminopropyl) diethylene glycol r, polyoxypropylenediamine,polyetherdiamine, polyoxyethylenediamine, triethyleneglycol diamine andmixtures thereof. For some embodiments, the diamine may be hydrophilicand the polyglycidyl ether may be hydrophilic prior to curing. For someembodiments, the diamine may be hydrophilic and the polyglycidyl etheris hydrophobic prior to curing. For some embodiments, the diamine may behydrophobic and the polyglycidyl ether may be hydrophilic prior tocuring.

Other inflation materials that may be used for some embodiments includepolyethylene oxide materials and neopentyl glycol diacrylate materialswhich are discussed in U.S. Pat. Nos. 6,610,035 and 6,176,849, which areincorporated by reference herein in their entirety. U.S. Pat. No.7,147,660, the contents of which are incorporated herein by reference,also includes inflation material embodiments that may be used forembodiments discussed herein.

FIGS. 3 through 5 show a bifurcated embodiment of a graft assembly 110for treatment of an abdominal aortic aneurysm. The graft assembly 110includes a bifurcated main graft member 112, having a proximal end 114and distal end 116. At the distal end 116, the assembly 110 includes abifurcated portion, including a first branched leg 118 (having a firstleg lumen 119) and a second branched leg 120 (having a second leg lumen121). In some embodiments, the first branched leg 118 may be referred toas an “ipsilateral leg” 118, and the second branched leg 120 may bereferred to as a “contralateral leg” 120. The main graft 112 includes atubular inner main fluid flow lumen 123 disposed therein. The lumen 123extends from the proximal end 114 of the graft body 112 to the distalbifurcated region 116. The proximal end 114 includes a proximal anchormember 122, including a proximal stent 124 and proximal connector ring126, as described above.

The proximal end 114 of the main body portion 112 includes at least oneinflatable channel 128. The inflatable channel 128 located closest tothe proximal end 114 may be considered an inflatable cuff (designated128′). The first branched leg 118 includes at least one first branchedcircumferential inflatable channel 130, and the second branched leg 120includes at least one second branched circumferential inflatable channel132. The first branched leg 118 may include at least two first branchedcircumferential inflatable channels 130, and the second branched leg 118includes at least two second branched circumferential inflatablechannels 132. As explained above, the circumferential inflatablechannels (including 128, 130, and 132) may extend the entirecircumference of the graft body 112, first branched leg 118 or secondbranched leg 120, respectively, or may extend only a portion of thecircumference. As depicted in FIGS. 3 and 4, the first branchedcircumferential inflatable channels 130 disposed furthest away from theproximal end 114 may extend the entire circumference of the firstbranched leg 118, while the first branched circumferential inflatablechannels 130 disposed closest to the proximal end 114 may extend only aportion of the circumference of the first branched leg 118. A similararrangement is desired for the second branched leg 120 and the secondcircumferential inflatable channels 132.

The first branched leg 118 of the main graft 112 has a first branchedleg inflatable fill channel 134, which is in fluid communication withthe first branched inflatable channels 130 and the proximal inflatablechannel(s) 128. Similarly, the second branched leg 120 includes a secondbranched leg inflatable fill channel 136, which is in fluidcommunication with the second branched circumferential inflatablechannels 132 and the proximal inflatable channel(s) 128. The main graft112, first branched leg 118 and second branched leg 120 form abifurcated “Y” shaped configuration.

The main fluid flow lumen 123 of the main graft 112 generally may have alarger transverse dimension and area than a transverse dimension andarea of either of the leg lumens 119 and 121 (shown in FIG. 3) of thefirst branched leg 118 or second branched leg 120, respectively. Aproximal anchor member 122 is disposed at a proximal end 114 of the maingraft 112. The proximal anchor member 122 includes a proximalself-expanding stent 124 that is formed from an elongate element havinga generally serpentine shape with four crowns or apices at either end,as explained above. A distal end of the proximal stent 124 may bemechanically coupled to a connector ring 126 which is embedded in graftmaterial of the proximal end 114 of the main graft 112, or directlycoupled to perforations in the proximal edge region of the main graft112. Embodiments of the connector ring 126 may be generally circular inshape have regular undulations about the circumference that may besubstantially sinusoidal in shape. The proximal stent 124 includesoutwardly extending barbs 125, which may be integrally formed with thestruts of the stent for some embodiments, having sharp tissuepenetrating tips that are configured to penetrate into tissue of aninside surface of a lumen within which the proximal stent 124 isdeployed in an expanded state. Although the proximal anchor member 122is shown as including self-expanding stent 124, similar stents may beused that are configured to be inelastically expanded with outwardradial pressure as might be generated by the expansion of an expandableballoon from within stent 124. The connector ring coupled to theproximal stent 124 may also be inelastically expandable.

In a desired embodiment, at least one of the first branched leg 118 andthe second branched leg 120 includes at least two inflatable channels.Thus, the first branched leg 118 may include at least two inflatablechannels 130, and the second branched leg 120 includes at least twoinflatable channels 132. The inflatable channel (130, 132) which isdisposed furthest from the proximal end 114 of the graft body 112 mayserve as a cuff, as explained above. The inflatable channels 130, 132may extend around the entire circumference of the leg 118, 120, or mayextend only partially around the circumference. In one embodiment, asmay best be seen in FIGS. 3 and 4, the inflatable channels 130, 132which are located closest to the main body portion 112 (labeled 130′,130″, 132′ and 132″) may only extend a portion of the circumference ofthe leg (118, 120, respectively). Such configuration allows for controlwhile implanting and securing the graft 10 in a patient.

To provide added rigidity and stiffness to the device, it may bedesirable to include a longitudinal channel between at least twoinflatable channels. For example, first branched leg 118 may include atleast two inflatable channels 130, with a longitudinal channel 138disposed between at least two inflatable channels 130 and in fluidcommunication therewith. Similarly, second branched leg 120 may includeat least two inflatable channels 132, with a longitudinal channel 140disposed between at least two inflatable channels 132 and in fluidcommunication therewith. Longitudinal channels 138, 140 may be onechannel or they may include a plurality of channels each incommunication with adjacent circumferential inflatable channels (130,132, respectively). It is desired to have a first longitudinal fillchannel 134 extend along the first branched leg 118 to the proximal end114 of the graft body 112, where the first longitudinal fill channel 134is in fluid communication with the proximal circumferential inflatablechannel(s) 128 and first inflatable channel(s) 130. Similarly, it isdesired to have a second longitudinal fill channel 136 extend along thesecond branched leg 120 to the proximal end 114 of the graft body 112,where the second longitudinal fill channel 136 is in fluid communicationwith the proximal circumferential inflatable channel(s) 128 and secondinflatable channel(s) 132. The use of longitudinal inflatable fillchannels 134, 136 allow for controlled delivery of fluid to the variouschannels (including 128, 130, 132, 138 and 140).

FIG. 5 depicts an alternate embodiment of FIGS. 3 and 4, which includesa plurality of longitudinal channels connecting individual leg channels.In this embodiment, bifurcated graft assembly 50 includes a main graftportion 52 having a proximal end 54 and two branched legs 56, 58opposite the proximal end 54. Each of the branched legs 56, 58 includesa series of circumferential inflatable channels. First branched leg 56includes a series of first circumferential inflatable channels 60Athrough 60E. Each of the first circumferential inflatable channels 60Athrough 60E may extend the entire circumference of first branched leg56, or may only extend around a portion of the circumference of firstbranched leg 56. The first circumferential inflatable channel(s) 60Athrough 60C located furthest from the proximal end 54 may extend theentire circumference of the first branched leg 56. Those channel(s) 60A(optionally 60B, 60C) located furthest from the proximal end 54 may beconsidered first leg cuff(s), as explained above. Similarly, secondbranched leg 58 includes a series of second circumferential inflatablechannels 62A through 62E. Each of the second circumferential inflatablechannels 62A through 62E may extend the entire circumference of secondbranched leg 58, or may only extend around a portion of thecircumference of second branched leg 58. The second circumferentialinflatable channel(s) 62A through 62C located furthest from the proximalend 54 may extend the entire circumference of the second branched leg58. Those channel(s) 62A (optionally 62B, 62C) located furthest from theproximal end 54 may be considered first leg cuff(s), as explained above.

Each of the first branched leg 56 and second branched leg 58 thusincludes a series of inflatable channels (generally 60, 62,respectively). To add rigidity and strength to the device during use, itmay be desirable to include at least one longitudinal channel between atleast two inflatable channels and in fluid communication therewith.Thus, in this embodiment, there may be at least one first longitudinalchannel 64 between at least two first circumferential inflatablechannels 60, and there may be at least one second longitudinal channel66 between at least two second circumferential inflatable channels 62.For example, first branched leg 56 may include first circumferentialinflatable channels 60C through 60E, which are connected by and in fluidcommunication with second longitudinal inflatable channels 64A, 64B.Again, similarly, second branched leg 58 may include secondcircumferential inflatable channels 62C through 62E, which are connectedby and in fluid communication with second longitudinal inflatablechannels 66A, 66B. Any number of circumferential inflatable channels(60, 62) may be used, and any number of longitudinal inflatable channels(64, 66) may be used. Each leg 56, 58 may include between 2 and 8circumferential inflatable channels (60, 62), and each leg 56, 58includes between 1 and 4 longitudinal inflatable channels (64, 66).

FIG. 6 depicts a modular bifurcated graft assembly 110, which generallyincludes the bifurcated assembly described above (in FIGS. 3 through 4),but includes optional first and second graft extensions 142, 144. Aswith the assembly described above, modular bifurcated graft assembly 110includes a generally tubular main graft body 112, which has a proximalend 114 and distal end 116, with first and second branched legs 118, 120disposed at the distal end 116. The assembly 110 includes a generallytubular lumen 123 extending through the main graft portion 112 to thebifurcated region and through the lumens (119, 121) of the first andsecond branched legs 118, 120. The proximal end 114 may include ananchoring device 122, a proximal stent 124, and proximal connector ring126 connecting the main graft body 112 with the proximal stent 124. Theproximal end 114 of the main graft body portion 112 may include one ormore proximal circumferential inflatable channel(s) 128, 128′. As withabove, the proximal circumferential inflatable channel 128 disposedclosest to the proximal end 114 may be considered an inflatable cuff.

Each of the first and second branched legs 118, 120 includes a series ofcircumferential inflatable channels (first circumferential inflatablechannels 130 and second circumferential inflatable channels 132). Anynumber of circumferential inflatable channels (130, 132) may be usedand, as explained above, individual circumferential inflatable channels(130, 132) may extend either the entire circumference of theirrespective leg (118, 120) or only partially around the circumference. Ina desirable embodiment, each leg (118, 120) includes at least twocircumferential inflatable channels (130, 132), respectively. It may bedesirable to include a first inflatable fill channel 134, which extendsalong the first branched leg 118 to the proximal end 114 of main graftbody 112, and which is in fluid communication with each of the firstcircumferential inflatable channel(s) 130 and proximal inflatablechannel(s) 128. Similarly, it may be desirable to include a secondinflatable fill channel 136, which extends along the second branched leg120 to the proximal end 114 of main graft body 112, and which is influid communication with each of the second circumferential inflatablechannel(s) 132 and proximal inflatable channel(s) 128′.

To provide added rigidity and support to the device, it may be desirablethat each leg (118, 120) includes a longitudinal inflatable channelbetween at least two circumferential inflatable channels. Thus, firstbranched leg 118 may include a first longitudinal inflatable channel138, which is between and in fluid communication with at least two firstcircumferential inflatable channels 130. Similarly, second branched leg120 may include a second longitudinal inflatable channel 140, which isbetween and in fluid communication with at least two secondcircumferential inflatable channels 132.

Modular bifurcated graft assembly 110 may include one or two stent graftextensions 142, 144. The first graft extension 142 has a first fluidflow lumen 146 disposed therein. The first graft extension 142 has anouter surface which may be sized and configured to be sealed to aninside surface of the first branched leg 118 of the main graft 112 withthe inner fluid flow lumen 146 of the first graft extension 142 in fluidcommunication with the fluid flow lumen of the first branched leg 118.Typically, an outside surface 150 of the first graft extension 142 maybe sealed to an inside surface of the first branched leg 118 of the maingraft 112 when the first graft extension 142 is in a deployed state.Similarly, the second graft extension 144 has a fluid flow lumen 148disposed therein. The second graft extension 144 has an outer surface152 which may be sized and configured to be sealed to an inside surfaceof the second branched leg 120 of the main graft 112 with the secondfluid flow lumen 148 in fluid communication with the fluid flow lumen ofthe second branched leg 120. Typically, an outside surface 152 of thesecond graft extension 144 may be sealed to an inside surface of thesecond branched leg 120 of the main graft 112 when the second graftextension 144 is in a deployed state.

For some embodiments, the axial length of the first and second branchedlegs 118 and 120 may be sufficient to provide adequate surface areacontact between outer surfaces 150 and 152 of first and second graftextensions 142 and 144. Additionally, the respective inside surfaces ofthe first and second branched legs 118 and 120 should provide sufficientfriction to the first and second outer surfaces 150, 152 to hold thefirst and second graft extensions 142 and 146 in place. Expandablemembers, such as expandable anchor members and the like, may be used toexpand the graft extensions 142 and 144 against the inside surfaces ofthe fluid flow lumens of the first and second branched legs 118 and 120.Varying the amount of overlap between the legs and extensions can allowfor different effective overall graft lengths to be achieved, therebyaccommodating a range of anatomical sizes with fewer distinct main bodyand extension dimensions than would otherwise be required. For someembodiments, the first and second branched legs 118 and 120 may have anaxial length of at least about 1 cm. For some embodiments, the first andsecond branched legs 118 and 120 may have an axial length of about 2 cmto about 6 cm, more specifically, about 3 cm to about 5 cm.

Some embodiments of main graft member 112 may include about 1 to about 8circumferential inflatable channels 130,132 disposed about each leg 118,120 and about 1 to about 8 proximal circumferential channels 128disposed about a main body portion of the main graft member 112. Someembodiments of the main graft body member 112 may include about 1 toabout 4 longitudinal or axial inflatable fill channels 134, 136 that mayserve to connect the circumferential inflatable channels (128, 130,132). Some embodiments of the circumferential channels may extend a fullcircumference of the graft section upon which they are disposed, or theymay extend only partially around the graft section upon which they aredisposed. For the main graft member embodiment 112 shown in FIG. 6, thenetwork of proximal inflatable channels 128, 128′ includes an inflatablecuff 128′ disposed adjacent the proximal end 114 of the main bodyportion 112 and a circumferential channel 128 disposed just distal ofthe inflatable cuff 128′. Each leg 118 and 120 of the main graft member112 includes 3 complete circumferential inflatable channels 130, 132 inaxial series. Each leg 118 and 120 of the main graft member 112 also hastwo partial circumferential inflatable channels 130, 132 disposedproximally of the complete circumferential inflatable channels 130, 132.

For some method embodiments of treating the vasculature of a patient, amodular graft assembly, such as the modular graft assembly embodiments110 discussed above, may be used. Various methods of delivery systemsand delivery of the device into a patient include those described inApplicant's co-pending application, U.S. Patent Application PublicationNo. 2009/0099649, the contents of which are incorporated by reference inentirety herein. For endovascular methods, access to a patient'svasculature may be achieved by performing an arteriotomy or cut down tothe patient's femoral artery or by other common techniques, such as thepercutaneous Seldinger technique. For such techniques, a delivery sheath(not shown) may be placed in communication with the interior of thepatient's vessel such as the femoral artery with the use of a dilatorand guidewire assembly. Once the delivery sheath is positioned, accessto the patient's vasculature may be achieved through the delivery sheathwhich may optionally be sealed by a hemostasis valve or other suitablemechanism. For some procedures, it may be necessary to obtain access viaa delivery sheath or other suitable means to both femoral arteries of apatient with the delivery sheaths directed upstream towards thepatient's aorta. In some applications a delivery sheath may not beneeded and a delivery catheter may be directly inserted into thepatient's access vessel by either arteriotomy or percutaneous puncture.

FIG. 7 depicts the assembly of FIG. 6 in a deployed state. As can beseen, in its deployed state, the modular bifurcated graft assemblyincludes a first and second stent graft extension 142, 144 disposed inthe first and second branched legs 118, 120. The main body portion 112and first and second branched legs 118, 120 span or substantially spanthe diseased region of abdominal aorta or aneurysm 162, providing safepassage therethrough. The proximal end 114 of the main graft body 112engages the inner wall 166 of the aorta 164 near, and typically prior,the renal arteries 163. A portion of the anchoring device 122 may bridgethe renal arteries 163. As can be seen, in this embodiment, the proximalcircumferential inflatable channel 128′ acts as a cuff, holding theassembly 110 in place. The first and second stent graft extensions 142,144 may extend from above the hypogastric arteries 168 and into and/orthrough the iliac arteries 170.

The first and second graft extensions 142 and 144 may be formed from aninner layer or layers and outer layer or layers of flexible graftmaterial, such as PTFE or ePTFE. In one embodiment, the flexible graftmaterial includes PTFE which is substantially porous but includes nodiscernable node and fibril structure. The inner and outer layers ofgraft material may be formed from tubular extrusions, laminated wraps ofmultiple layers of graft material or materials, and the like. The inneror outer layers of graft material may be permeable, semi-permeable orsubstantially non-permeable for some embodiments. For some embodiments,the nominal length of the extensions 142 and 144 may be permeable withone or more longitudinal sections, such as a middle longitudinalsection, being semi-permeable or non-permeable. Some embodiments of thegraft extensions 142 and 144 may have an overall tapered or flaredconfiguration with a nominal inner lumen that tapers or flares when thegraft extension is in a relaxed expanded state. For embodiments thatinclude laminated wraps of material, the wraps may be carried outcircumferentially, helically or in any other suitable configuration.

The first and second leg extensions 142, 144 are desirably stent-graftdevices. A first radially expandable stent 154 may be interposed betweenan outer layer 150 and inner layer 158 of graft material. A secondradially expandable stent 156 may be interposed between an outer layer152 and inner layer 160 of graft material. The interposed stent 154, 156disposed between the outer layer150, 152 and inner layer 158, 160,respectively, of graft material may be formed from an elongate resilientelement helically wound with a plurality of longitudinally spaced turnsinto an open tubular configuration. The helically wound stent 154, 156may be configured to be a self-expanding stent or radially expandable inan inelastic manner actuated by an outward radial force from a devicesuch as an expandable balloon or the like. Some tubular prosthesisembodiments that may be used for graft extensions 142 and 144 arediscussed in U.S. Pat. No. 6,673,103 to Golds et al., titled “Mesh andStent for Increased Flexibility”, which is hereby incorporated byreference in its entirety herein.

The graft extensions 142 and 144 may optionally include attachmentelements disposed on outer surfaces 150, 152 of their respectiveproximal ends or sections that may be used to couple to correspondingattachment elements disposed on inside surfaces of the respective firstbranched leg 118 and second branched leg 120 of the main graft 112.Attachment element embodiments that may be used on outside surfaces 150and 152 of the graft extensions 142 and 144 and inside surfaces of firstand second branched legs 118 and 120 of the main graft 112 may includeany of the attachment elements in U.S. Patent Application PublicationNo.205/0228484, entitled “Modular Endovascular Graft”, by Stephens, etal., which is hereby incorporated by reference herein in its entirety.The first graft body section may have a first wall portion and a firstattachment element disposed on the first wall portion and the secondgraft body section may have a second attachment element disposed on asecond wall portion of the second graft body section. The secondattachment element may be configured to be secured to the firstattachment element with respective fluid flow lumens of the first andsecond graft body sections sealed together. For some embodiments, thefirst and second attachment elements may be secured together in anoverlapped portion of the first and second graft body sections. For someembodiments, the first attachment element may include a plurality offlexible hooks and the second attachment element includes a plurality offlexible loops adjacent each other wherein the flexible hooks areconfigured to mechanically engage the flexible loops when the first andsecond attachment elements are pressed together. For some embodiments,the first attachment element includes a plurality of buttons having anenlarged head portion regularly spaced from each other on a surface afirst wall portion and a second attachment element includes anexpandable mesh having a plurality of apertures configured to allowentry of the enlarged head portion of the buttons while the mesh is in acircumferentially constrained state and to capture the enlarged headportion of the buttons when the mesh is in a circumferentially expandedstate. For some embodiments, the first attachment element includes aplurality of pins radially extending from a surface of a first wallportion and the second attachment element includes an expandable meshhaving a plurality of apertures configured to allow entry of the pinswhen the first attachment element is pressed against the secondattachment element. For some embodiments the first attachment elementmay include an inflatable cuff containing curable material and thesecond attachment element includes an expandable member with barbsconfigured to extend outwardly into the inflatable cuff and curablematerial.

Graft extensions 142 and 144, which may be interchangeable for someembodiments, or any other suitable extension devices or portions of themain graft section 112 may include a variety of suitable configurations.Alternatively, the graft extensions 142, 144 may be useful as a separateendovascular stent graft, apart from the bifurcated graft assembly 110.For some embodiments, graft extensions 142 and 144 may include a PTFEcovered helical nitinol stent 154, 156 as discussed above with layers ofPTFE having a variety of characteristics. Regarding the stent 154, 156,it may be formed from an elongate resilient element which is helicallywound with a plurality of longitudinally spaced turns.

Some stent embodiments may be generally helical in configuration withserpentine or other regularly spaced undulations transverse to thehelical path of the elongate stent element as shown in more detail inFIGS. 8 through 11. As can be seen, a generally tubular stent 300 may beprovided. The tubular stent 300 includes a helically-wound, undulatingwire forming a series of adjacent helical windings 302, which may bemade from the materials described above (including a resilient metalsuch as nitinol). The ends 304, 306 of the stent 300 may be secured toadjacent ring portions of the stent at distinct areas. For example, afirst end may be adjoined via a first securement point 308, and a secondend may be joined at a second securement point 310, as shown to avoidexposure of element ends to either PTFE graft material or possiblepatient tissues. In a preferred embodiment, the securement points 308,310 are located proximal to the first end 304 and second end 306,respectively, with no other securement points on the stent 300. That is,aside from the helical windings 302 at the first end 304 and second end306, respectively, adjacent approximate circumferential windings 302 inthe stent 300 may be free of interconnecting securement points. Anysecurement means may be used, including, for example, welding, such asstruts and welds. It is desired that the relative stiffness of a stentbe greater than the stiffness of the PTFE graft material so as toprovide beneficial kink resistance.

The undulating wire may be a continuous element forming a series ofhelical windings 302 extending from one end 304 of the extension to theother end 306 thereof. The tubular stent 300 thus has an internal lumen320 extending therethrough, from the first end 304 to the second end306. The ends 304, 306 of the elongate element may be secured toadjacent ring members by any suitable means such as adhesive bonding,welding such as laser welding, soldering or the like. For someembodiments, the stent element may have a transverse dimension ordiameter of about 0.005 inch to about 0.015 inch. As may be seen inFIGS. 9A and 9B, the stent 300 may be tapered or flared. In addition, ifdesired, adjacent helical windings 302 may be arranged 315 such thatadjacent helical windings 302 at one end (either the first end 304 orsecond end 306) have an acute angle formation at a portion of the stent300 proximal to the end of the stent 300. That is, if desired, thehelical winding closest to the end (shown as 302′) may have anapproximately 180° angle with respect to the longitudinal axis, whilethe helical winding next to this helical winding (shown as 302″) has anangle less than 180°. These two helical windings (302′ and 302″) may beattached at securement points 308, 310.

FIG. 10A through 10E depicts various arrangements of the helicalwindings 302 formed by the undulating wire in forming the stent 300.Adjacent helical windings are depicted as 302A and 302B, but it will beunderstood that the arrangement depicted in FIGS. 10A through 10E may beapplied to each helical winding 302 in the stent 300. Alternatively, thearrangements depicted in FIGS. 10A through 10E may be applied to onlysome of the helical windings 302 in the stent 300. Undulating wire ofthe stent 300 includes a series of peaks 312 and valleys 314 as the wireis helically wound. The arrangement of peaks 312 and valleys 314 mayvary and may be arranged in any fashion desired. In some embodiments,such as that of FIG. 10A, the peaks 312 of one circumferential winding302A may be substantially aligned with the peaks 312 of an adjacentcircumferential winding 302B. As can be seen in FIG. 10B, the adjacentcircumferential windings 302A and 302B may be spaced apart. As can beseen in FIG. 10C, the adjacent circumferential windings 302A and 302Bmay be closer together. In another embodiment, set forth in FIG. 10D,one peak 312 of one circumferential winding 302B may span two peaks 312of an adjacent winding 302A. In another embodiment set forth in FIG.10E, the peaks 312 of one circumferential winding 302A may besubstantially aligned with the valleys 314 of an adjacentcircumferential winding 302B. Other arrangements for the helicalwindings 302 are contemplated and will be readily understood by those ofskill in the art.

The distances between adjacent windings 302A, 302B may vary along thelength of the stent 300, where the distance at one end 304 is differentthan the distance at the second end 306. In each embodiment, there aretwo distances that should be considered. The first distance X is thedistance between the lowest valley (314) of the first winding (302A) andthe highest peak (312) of the second winding (302B). The second distanceY is the distance between the highest peak (312) and lowest valley (314)of the first winding (302A).

There may be at least two different ratios of X/Y

$\left( {{or}\mspace{14mu} {equivalently}\mspace{14mu} \frac{X}{Y}} \right)$

present in the device, including but limited to three different relativeratios of these distances X/Y. The first ratio is where X/Y is arelatively large positive number, that is, there is a relatively largerseparation between the distance (X) as compared to the distance (Y). Thesecond ratio is where X/Y is a relatively smaller positive number, thatis, there is a relatively smaller separation between the distance (X) ascompared to the distance (Y). Finally, the third ratio is where X/Y is anegative number, that is, the lowest peak of the first winding (302A)dips to a point lower than the highest peak of the second winding(302B). An example of a negative ratio is seen in FIG. 10C, where anegative value for X can be seen.

The ratio X/Y can be manipulated to obtain the desired properties of thestent graft in a local region. A relatively large X/Y ratio (preferablygreater than about 0.5) produces a highly flexible region of a stentgraft. A smaller X/Y ratio (preferably from about 0.1 to about 0.5)produces regions of a stent graft with moderate flexibility and moderateradial force. A region of a stent graft with an even smaller or negativeX/Y ratio (preferably less than about 0.1) has a relatively high radialforce with relatively less flexibility. The above ranges for X/Y areappropriate when the stent height Y is from about one-third of thediameter of the stent to about equal to the diameter of the stent. If Yis larger than this when compared to D, then the ranges for the X/Yratios quoted above will be reduced. Similarly, if Y is much smallerthan the stent diameter D, then the numerical values for the rangesabove will be increased.

Using the principle described above, a stent graft can be constructedwith varying ratios of X/Y along the length to achieve desiredproperties. For example, if a stent graft is used as an iliac limb in amodular endovascular graft for abdominal aortic aneurysms (AAAs), it maybe desirable for the proximal end of the stent graft to have arelatively high radial force to maximize anchorage into the aortic bodycomponent of the modular system. In this case, the proximal end of theiliac limb could be designed with a small or negative X/Y ratio, such as−0.5, and Y may be chosen to be, for example, from about one fifth toone half of the stent graft diameter. In this region flexibility is lessimportant than radial force so the negative X/Y ratio yields the desiredproperties. In the middle of the stent graft flexibility becomesimportant to accommodate the tortuous common iliac arteries often foundin AAA patients. It may then be desirable to have a relatively large X/Yratio, such as about 0.55 , to achieve this flexibility. Near the distalend of the stent graft it may again be desirable to have more radialforce to promote anchorage and sealing of the iliac limb into the commoniliac artery of the patient, but not as much radial force as at theproximal end. In this case, it may be desirable to have an X/Y rationear zero, or from about −0.1 to about 0.3.

Since the stent is formed in a helix along the length of the stentgraft, it is possible to continuously vary the X/Y ratio to achieve thedesired properties in various regions of the stent graft with smoothvariations and no abrupt changes along the length. These smoothvariations promote conformance to the vasculature and avoid the stressand/or strain concentrations and potential kinking that can result fromabrupt transitions in mechanical properties along the length of a stentgraft.

The stent 300 may include a longitudinal axis (generally defined alonginternal lumen 320) and a radial axis perpendicular to the longitudinalaxis; where the helical windings 302 are wound at an acute winding angleof about 3 degrees to about 15 degrees with respect to the radial axis.As can be seen in FIGS. 9A and 9B, the acute winding angle at a portionof the stent 300 proximal to the first end 304 is different from theacute winding angle at a portion of the stent 300 proximal to the secondend 306. In some embodiments, a first helical winding 302 at the firstend 304 may be perpendicular to the longitudinal axis. Further, it maybe desired that a helical winding 302 at the second end 306 isperpendicular to the longitudinal axis. Helical windings 302 at thefirst end 304 and the second end 306 may both be perpendicular to thelongitudinal axis, or only one may be perpendicular to the longitudinalaxis. An adjacent peak 312 and an adjacent valley 314 of a helicalwinding 302 have a peak height from an apex of said adjacent peak to abase of said adjacent valley. It may be desired that the peak height ata portion of the stent 300 proximal to the first end 304 of the stent300 is different from the peak height at a portion of the stent 300proximal to the second end 306 of the stent 300.

At least one graft layer may be disposed on the stent 300. The placementof the graft layers may best be seen in FIGS. 11A through 12. In someembodiments, an inner graft layer 318 may be disposed on the interiorsurface of the helically wound stent 300, forming inner lumen 320. Asecond graft layer 316 may be disposed on the outer surface of thehelically wound stent 300, forming an outside surface. More than one ortwo layers of graft material may be disposed on the interior or exteriorof the helically wound stent 300 as desired. For some embodiments offirst or second graft extensions 142, 144, layers of materials havingdifferent properties may be used in combination to achieve a desiredclinical performance. For example, some layers of PTFE covering thestent 300 may be permeable, semi-permeable or substantiallynon-permeable depending on the desired performance and materialproperties. The layers 316 and 318 may be applied by a variety ofmethods and have a variety of configurations. For example, some layerembodiments may include extruded tubular structures applied axially overa mandrel or subassembly. Some layer embodiments 316 and 318 may beapplied by wrapping layers circumferentially or wrapping tapes orribbons in an overlapping helical pattern. For some embodiments, theouter layer 316 may be made from or include a semi-permeable orsubstantially non-permeable PTFE layer and the inner layer 318 may bemade of or include a permeable layer of PTFE.

The first and/or second graft extensions 142, 144 may be made by formingthe layers of material 316, 318 together with the helically wound stent300 over a mandrel, such as a cylindrical mandrel (not shown). Once theinnermost layer 316 of the extension 142, 144 has been wrapped about ashaped mandrel, a helical nitinol stent, such as helical stent 300, maybe placed over the innermost layered PTFE layer 316 and underlyingmandrel. If desired, one or more additional layers 318 of graft materialmay be wrapped or otherwise added over the exterior of the stent 300. Ifdesired, the outer layer 318 may include low permeability PTFE film orPTFE film having substantially no permeability that does not have thetraditional node fibril microstructure. The mandrel may then be coveredwith a flexible tube such that the layers 316, 318 and stent 300 aresandwiched under pressure and sintered so as to raise the temperaturefor the PTFE material to undergo a melt transformation in order to lockin its geometry and strength. The flexible tube (a manufacturing aid notshown) is removed from over the device and the resultant graft extension(142, 144) is removed from the mandrel.

It may be desirable to include at least one series of crimps in thegraft material for one or both graft extensions 142, 144. As depicted inFIGS. 13 and 14, a crimped stent graft 350 may be formed. The crimpedstent graft 350 includes a helically wound stent 300 described abovehaving a first end 304 and a second end 306 and tubular lumen 320extending therebetween, with at least one layer of graft materialdisposed thereon. Both an interior layer 318 and exterior layer 316 ofgraft material may be disposed on the stent 300. The crimped stent graft350 includes at least one crimped region 352 disposed between at leasttwo adjacent windings 302A, 302A. The crimped region 352 may extend aslong as the space between adjacent windings 302A, 302B. Alternatively,the crimped region 352 may extend only as long as a portion of the spacebetween adjacent windings 302A, 302B. The length of the crimped regionis designated by the line depicted as Z on FIG. 13. The crimped region352 includes a plurality of crimps 354, which are portions of graftmaterial which have been compressed and form a crimping configuration.The crimped stent graft 350 may include a crimped region 352 betweeneach adjacent winding 302A, 302B of the stent 300. The crimps 354 mayextend around the entire circumference of the crimped stent graft 350,or may extend only a portion of the circumference of the crimped stentgraft 350. As can be seen in FIG. 14, the crimps 354 may have agenerally semi-circular configuration.

The crimped stent graft 350 may be formed through any desired means. Inone embodiment, the crimped stent graft 350 is formed through a firstmethod. This first method includes the steps of forming a generallytubular, helically wound stent 300 as described above. The helicallywound stent 300 is then axially stretched, forming an axially stretchedhelically wound stent. A first graft liner is disposed on the interiorlumen 320 of the helically wound stent 300, thus forming a first graftlayer 318. The first graft layer 318 may be disposed before the stent300 is placed on a mandrel or after the stent 300 is placed on amandrel. The first graft layer 318 may then be attached to the stent300. The first graft layer 318 may be made of porous PTFE having nodiscernable node and fibril structure, but may be made from othermaterials as described above. A discernable node and fibril structuremay be observed and/or measured through the use of a scanning electronmicroscope (SEM). Porous PTFE of the present invention may have nodiscernable node and fibril structure even at about 20,000× (20,000times) magnification under SEM or the like. Such magnification is notlimiting and other magnifications, such as 10,000× or greater may beused. A graft covering is then disposed on the outer surface of theaxially stretched tubular stent 300, the graft covering thus forming asecond graft layer 316. Again, the second graft layer 316 may be made ofporous PTFE having no discernable node and fibril structure, but may bemade from other materials as described above. The second graft layer 316may be attached to the stent 300 via any desired means. Finally, theaxially stretched tubular stent 300 is allowed to relax, forming acrimped region 352 including a plurality of crimps 354 in the firstgraft layer 318 and second graft layer 316.

Another method to form a crimped stent graft 350 is provided herein.This alternative embodiment includes providing a tubular stent 300, thetubular stent 300 having an inner surface (i.e., a lumen 320 extendingtherethrough) and an outer surface. The stent may include an undulatingwire having opposed first and second ends and being helically wound intoa plurality of approximate circumferential windings 302 to define astent wall. Further, the undulating wire may have a pluralityundulations defined by peaks 312 and valleys 314 with peaks of adjacentapproximate circumferential windings 302 being separated by a desireddistance. As described above, the distance between adjacent windings 302may be any desired distance, and in particular is most desirably thedistance explained above. A graft liner is disposed on the inner lumen320 of the tubular stent, forming a first graft layer 318. The firstgraft layer 318 may be made from porous PTFE having no discernable nodeand fibril structure, or alternatively may be made from otherbiocompatible materials described above. A graft covering may then bedisposed on the outer surface of the tubular stent 300, forming a secondgraft layer 316. As with the first graft layer 318, the second graftlayer 316 may be made from porous PTFE having no discernable node andfibril structure, but may be made from any materials described above.The tubular stent 300, first graft layer 318 and second graft layer 316are disposed on a shaped mandrel (not shown), the shaped mandrelincluding at least one crimp shape on its outer surface. The crimp shapemay be aligned so that the crimp shape is disposed between adjacenthelical windings 302 of the stent 300. Then, the assembly may be heatedand sintered, thus forming a crimped stent graft 350 including at leastone crimp region 352 including a plurality of crimps 354. The crimps 354of the crimped region 352 will generally conform to the crimp shape ofthe shaped mandrel.

In addition, for some embodiments, an adhesive such as FEP or the likemay be applied adjacent the stent 300 prior to the application of thePTFE layer(s) covering the stent, or at any other suitable time orlocation, in order to facilitate a bond between the stent element andthe PTFE materials adjacent the stent 300. For some embodiments, thepermeable PTFE material 318 may include an ePTFE material havinguniaxial expansion with a uniaxial node fibril structure. PTFE materialshaving a multiaxial node fibril orientation may also be used for someembodiments. For some embodiments, the permeable material may includeabout 1 to about 5 layers of material or more and have an inter nodaldistance of about 10 microns to about 30 microns. The permeable materialmay have a thickness for some embodiments of about 0.00005 inch to about0.005 inch.

For some embodiments, the low permeability non-expanded PTFE materialmay have a non-typical node fibril microstructure with essentially nonodal spacing and very low or no liquid permeability. The extensions142, 144 may include about 1 layer to about 5 layers of semi-permeableor substantially non-permeable PTFE material having a thickness of about0.0001 inches to about 0.005 inches, more specifically, about 0.0004inches to about 0.001 inches. Examples of such materials are describedin U.S. Patent Application Publication Nos. 2006/0233990 and2006/0233991 described above which are incorporated by reference intheir entirety herein.

For some embodiments, the PTFE material having low permeability orsubstantially no permeability may be made by providing a PTFE layer andapplying a stretching agent, such as isoparaffinic fluids, such as thosesold under the brand name Isopar™ by ExxonMobil Chemical Co., to atleast a portion of the PTFE layer and stretching the PTFE layer whilethe layer is wet with stretching agent. For some embodiments, the PTFElayer may be saturated with stretching agent while being stretched. Forsome embodiments, the PTFE layer may be stretched by a ratio of about2:1 to about 20:1. For some embodiments, the wet stretching of the PTFElayer is carried out in a direction transverse to the machine directionof expansion. For some embodiments, the wet stretching of the PTFE layeris carried out at a temperature of about 80° F. to about 130° F. Forsome embodiments, the PTFE layer provided is made by extruding acompounded PTFE resin through an extruder to form a PTFE ribbonextrudate. Such a PTFE material may have substantially low porosity, lowpermeability, no discernable node and fibril structure and a thicknessof about 0.00005 inch to about 0.005 inch. Some such PTFE materials mayalso have a closed cell microstructure with a plurality ofinterconnected high density regions having no discernable node andfibril structure between the high density regions. Some such PTFEmaterials may have low or no fluid permeability.

The transverse dimension or diameter of the main fluid flow lumen ofsome main graft embodiments 112 in a radially expanded state may be fromabout 12.0 mm to about 32.0 mm. The transverse dimension or diameter ofthe first and second branched leg fluid flow lumens 146, 148 may be fromabout 5 mm to about 20 mm for some embodiments. For some embodiments,the length of the legs 118 and 120 and may be from about 2 cm to about 6cm. The transverse dimension of some embodiments of the graft extensions142 and 144 when in a radially expanded state may be from about 5 mm toabout 26 mm. The axial length of some embodiments of the graftextensions 142 and 144 may be from about 2 cm to about 15 cm,specifically, about 5 cm to about 10 cm. Some embodiments of the firstand second extension grafts 142 and 144 may have outer transversedimensions or diameters of between about 10 mm to about 30 mm, morespecifically, between about 15 mm and 25 mm when in an expanded state.

The main graft 112 and graft portions of the first and second graftextensions 142 and 144 may be made at least partially frompolytetrafluoroethylene (PTFE) which may include expandedpolytetrafluoroethylene (ePTFE). In particular, main graft 112 and graftextensions 142 and 144 may include any number of layers of PTFE and/orePTFE, including from about 2 to about 15 layers, having an uncompressedlayered thickness of about 0.003 inch to about 0.015 inch for the supplegraft material or materials alone without supporting or ancillarystructures such as high strength stents, connector rings or the like.Such graft body sections may also include any alternative high strength,supple biocompatible materials, such as DACRON, suitable for graftapplications. Descriptions of various constructions of graft bodysections as well as other components of graft assembly 110 that may beused in any suitable combination for any of the embodiments discussedherein may be found in U.S. Pat. No. 7,125,464 to Chobotov, et al.,entitled “Method and Apparatus for Manufacturing an Endovascular GraftSection”; U.S. Patent No.7,090,693 to Chobotov et al., entitled“Endovascular Graft Joint and Method of Manufacture”; U.S. Pat. No.7,147,661, entitled “Method and Apparatus for Shape Forming EndovascularGraft Material”, to Chobotov et al.; U.S. Pat. No. 7,147,660 to byChobotov et al., entitled “Advanced Endovascular Graft”; U.S. PatentApplication Publication No. US 2006/0233990 to Humphrey et al. entitled“PTFE Layers and Methods of Manufacturing”; and U.S. Patent ApplicationPublication No. 2006/0233991 to Humphrey et al., entitled “PTFE Layersand Methods of Manufacturing”, the entirety of each of which isincorporated herein by reference.

It may be useful for some embodiments of the main graft 112 to have anominal axial length which is configured to allow the use of the maingraft 112 in a wide variety of vascular morphologies withsupplementation by one or more graft extensions 142 and 144. A modulargraft embodiment 110 is normally chosen in order to have a proper fit tothe patient's vasculature. For some graft indications, it is necessaryto produce a large number of size variations of the graft system, orgraft assembly 110 components, in order to accommodate the size andconfiguration variations of each patient's vasculature in order toachieve an acceptable fit of the graft assembly 110 within the patient'svasculature. This can be very costly and time consuming for themanufacturer of the endovascular graft assembly 110 and the hospitalswhich must maintain a comprehensive inventory of the devices. Inaddition, this may require an inconvenient amount of shelf space in thehospital operating room or catheter lab. For some embodiments, maingraft member 112 may have an axial length that is selected to allowanchoring of the proximal anchor member 122 adjacent the renal arteriesextending from a patient's aorta with the legs of the bifurcated portionremaining clear of the iliac arteries in a large cross section ofpatients having diverse physical size and vascular configurations. Inthis way, the need for customizing a graft assembly 110 for a particularpatient or group of patients can be avoided.

For some embodiments, the axial length of the main graft member 112, andparticularly the axial distance or separation between the proximalanchor member 122 and distal end of the first and second branched legs118 and 120 may be selected to extend across an abdominal aorticaneurysm without extending into the iliac arteries of a selectedpatient. A selected patient may be a member of a group of patients whohas the longest axial separation between the sealing point in the aortajust distal to the renal arteries and a distal most viable anchor andsealing point in the iliac arteries. In some embodiments for aparticular patient group, the proximal end of the main graft member 112is axially separated from the distal ends of the first and secondbranched legs 118 and 120 by a length of about 5 cm to about 10 cm, morespecifically, about 6 cm to about 8 cm.

For some embodiments of sizing a main graft member embodiment 112, theseparation of the proximal anchor member 122 and distal end of deployedgraft extensions 142 and 144 is selected such that the separation isjust long enough to span the separation between the renal arteries andthe proximal most anchor and sealing point in the iliac artery orarteries of a patient. This distance may be determined from the patient,in a selected group of patients, which has the longest such separationin the selected group of patients. In addition, for these embodiments,this separation must be shorter than the separation between the renalarteries and hypogastric artery or arteries. The distance may bedetermined from the patient, in the selected group of patients, that hasthe shortest such separation in the selected group of patients. In thisway, it may be possible to treat all members of a selected group ofpatients with a main graft member 112 embodiment or embodiments whichhave a common main graft body length. Such embodiments may be anchoredto the patient's aorta distal of the patient's renal arteries andanchored distally in the patient's iliac artery or arteries, withoutblocking either the renal arteries or hypogastric artery or arteries.Such a modular graft system embodiment 110 may have an overall lengthincluding the main graft member 112 and deployed graft extensions 142,144 of about 10 cm to about 22 cm, specifically, about 11 cm to about 20cm.

The careful sizing and configuring of the main graft 112 allows the useof a single main graft 112 embodiment or design to be adaptable to awide range of patients when supplemented by one or more graft extensions142, 144. More specifically, a main graft 112 having an axial length ofabout 5 cm to about 8 cm may be properly deployed in a large percentageof potential patients. Once deployed, the fluid flow lumens 146, 148 ofthe first and second graft extensions 142, 144 can then be sealed to thepatient's iliac arteries 170 with the deployment of graft extensions142, 144. Although the graft assembly 110 includes the option of usingattachment elements to secure the graft extensions 142, 144 to the firstand second branched legs 118, 120, this may not be necessary in mostcases and an adequate seal and mechanical fixation of a graft extensions142, 144 may be achieved with the use of a standard expandable member onthe graft extensions 142, 144 instead of an attachment element.

Some embodiments of a method of treating a patient include providing adelivery catheter containing a radially constrained bifurcated maingraft member 110. For some method embodiments of treating thevasculature of a patient, a modular graft assembly, such as the modulargraft assembly embodiments 110 discussed above, may be used. Forendovascular methods, access to a patient's vasculature may be achievedby performing an arteriotomy or cut down to the patient's femoral arteryor by other common techniques, such as the percutaneous Seldingertechnique. For such techniques, a delivery sheath (not shown) may beplaced in communication with the interior of the patient's vessel suchas the femoral artery with the use of a dilator and guidewire assembly.Once the delivery sheath is positioned, access to the patient'svasculature may be achieved through the delivery sheath which mayoptionally be sealed by a hemostasis valve or other suitable mechanism.For some procedures, it may be necessary to obtain access via a deliverysheath or other suitable means to both femoral arteries of a patientwith the delivery sheaths directed upstream towards the patient's vessel164 (such as the aorta). In some applications a delivery sheath may notbe needed and the delivery catheter may be directly inserted into thepatient's access vessel by either arteriotomy or percutaneous puncture.

Once the proximal anchor member 122 has been secured to the insidesurface 166 of the patient's vessel 164, the proximal inflatablechannels 128 (and in particular, the inflatable channel acting as a cuff128′) may then be filled through an inflation port in either the firstinflation fill channel 134 or the second inflatable fill channel 136with inflation material injected through an inflation tube. Suchinflation may serve to seal an outside surface of the inflatable cuff128′ to the inside surface 166 of the vessel 164. The remaining networkof inflatable channels 128, 130, 132 are also filled with pressurizedinflation material at the same time which provides a more rigid framelike structure to the graft 112 as shown in FIG. 8. In addition, thefirst and second longitudinal inflation channels 138, 140 are filledwith pressurized inflation material, giving even more strength andrigidity. For some embodiments, the inflation material may be a curableor hardenable material that may cured or hardened once the network ofinflatable channels are filled to a desired level of material orpressure within the network. Some embodiments may also employ radiopaqueinflation material to facilitate monitoring of the fill process andsubsequent engagement of graft extensions. The material may be cured byany of the suitable methods discussed herein including time lapse, heatapplication, application of electromagnetic energy, ultrasonic energyapplication, chemical adding or mixing or the like.

The network of inflatable channels 128, 130, 132, and the longitudinalinflation channels 138, 140, may be partially or fully inflated byinjection of a suitable inflation material into the main fill port toprovide rigidity to the assembly 110. Although it is desirable topartially or fully inflate the network of inflatable channels 128, 130,132 of the main graft 112 at an early stage of the deployment process,such inflation step optionally may be accomplished at a later stage ifnecessary.

For some embodiments, up to the time that the network of inflatablechannels 128, 130, 132, including the longitudinal inflation channels138, 140, have been filled with inflation material which has been curedor hardened, an elongate tether may be used to axially restrain thegraft 112 and prevent axial separation of the graft 112 from thedelivery catheter. A tether loops through the first and second lumens ofthe first and second branched legs 118, 120 of the graft member 112 andis secured to a handle on a proximal adapter (not shown) of the deliverycatheter. The tether is configured to have a length that is short enoughto mechanically restrain distal axial movement of the main graft member112 relative to the delivery catheter so as to prevent decoupling of aninflation tube from the inflatable fill channel 134, 136 of the maingraft member 112. Once the inflation material has been fully injectedinto the network of inflatable channels 128, 130, 132, including thelongitudinal inflation channels 138, 140 and cured or hardened, thetether may be released and removed to allow distal retraction of thedelivery catheter.

The following embodiments or aspects of the invention may be combined inany fashion and combination and be within the scope of the presentinvention, as follows:

Embodiment 1

An endovascular stent-graft comprising:

-   -   a tubular stent wall having opposed first and second ends;    -   an undulating wire having opposed first and second ends and        being helically wound into a plurality of approximate        circumferential windings to define said stent wall;    -   said undulating wire having a plurality undulations defined by        peaks and valleys;    -   peaks of adjacent approximate circumferential windings being        separated by a distance with said distance between adjacent        peaks at said first end being different from said distance        between adjacent peaks at said second end;    -   said first wire end secured to a first undulation at said first        end;    -   said second wire end secured to a second undulation at said        second end;    -   a graft liner comprising first plurality of layers of porous        PTFE having no discernable node and fibril structure; and    -   a graft covering comprising a second plurality of layers of        porous PTFE having no discernable node and fibril structure;    -   wherein said tubular stent wall is securably disposed between        said graft covering and said graft lining.

Embodiment 2

The endovascular stent-graft of embodiment 1, wherein said peaks of onecircumferential winding are substantially aligned with said peaks of anadjacent circumferential winding.

Embodiment 3

The endovascular stent-graft of embodiment 1, wherein said peaks of onecircumferential winding are substantially aligned with said valleys ofan adjacent circumferential winding.

Embodiment 4

The endovascular stent-graft of embodiment 1, wherein said endovascularstent-graft has a longitudinal axis and a radial axis perpendicular tosaid longitudinal axis; and wherein said undulating wire is helicallywound at an acute winding angle of about 3 degrees to about 15 degreeswith respect to said radial axis.

Embodiment 5

The endovascular stent-graft of embodiment 4, wherein said acute windingangle at a portion of said stent wall proximal to said first end of saidstent wall is different from said acute winding angle at a portion ofsaid stent wall proximal to said second end of said stent wall.

Embodiment 6

The endovascular stent-graft of embodiment 4, a first winding at saidfirst end is perpendicular to said longitudinal axis and wherein aterminal winding at said second end is perpendicular to saidlongitudinal axis.

Embodiment 7

The endovascular stent-graft of embodiment 1, wherein an adjacent peakand an adjacent valley of said undulating wire has a peak height from anapex of said adjacent peak to a base of said adjacent valley; andwherein said peak height at a portion of said stent wall proximal tosaid first end of said stent wall is different from said peak height ata portion of said stent wall proximal to said second end of said stentwall.

Embodiment 8

The endovascular stent-graft of embodiment 1, wherein, except for saidfirst and said second wire ends being secured to said first and secondundulations, respectively, adjacent approximate circumferential windingsare free of interconnecting struts and welds.

Embodiment 9

The endovascular stent-graft of embodiment 1, wherein said graft linerand said graft covering is crimped between said peaks of adjacentapproximate circumferential windings to provide crimped graft portions.

Embodiment 10

The endovascular stent-graft of embodiment 10, wherein said crimpedgraft portions are approximate circumferential crimped portions.

Embodiment 11

An endovascular stent-graft comprising:

-   -   a graft liner comprising first plurality of layers of porous        PTFE having no discernable node and fibril structure;    -   a graft covering comprising a second plurality of layers of        porous PTFE having no discernable node and fibril structure; and    -   a tubular stent securably disposed between said graft liner and        said graft cover; said stent comprising an undulating wire        having opposed first and second ends and being helically wound        into a plurality of approximate circumferential windings to        define    -   a stent wall; said undulating wire having a plurality        undulations defined by peaks and valleys with peaks of adjacent        approximate circumferential windings being separated by a        distance;    -   wherein said graft liner and said graft covering is crimped        between said peaks of adjacent approximate circumferential        windings to provide crimped graft portions.

Embodiment 12

The endovascular stent-graft of embodiment 11, wherein said crimpedgraft portions are approximate circumferential crimped portions.

Embodiment 13

A method of making a crimped stent graft, comprising the steps of:

-   -   a. providing a tubular stent having an inner surface and an        outer surface, said stent comprising an undulating wire having        opposed first and second ends and being helically wound into a        plurality of approximate circumferential windings to define a        stent wall; said undulating wire having a plurality undulations        defined by peaks and valleys with peaks of adjacent approximate        circumferential windings being separated by a distance;    -   b. axially stretching said tubular stent;    -   c. disposing a graft liner on said inner surface of said axially        stretched tubular stent, said graft liner comprising first        plurality of layers of porous PTFE having no discernable node        and fibril structure;    -   d. disposing a graft covering on said outer surface of said        axially stretched tubular stent, said graft covering comprising        a second plurality of layers of porous PTFE having no        discernable node and fibril structure; and    -   e. allowing said axially stretched tubular stent to relax,        forming crimps in said graft liner and said graft covering.

Embodiment 14

A method of making a crimped stent graft, comprising the steps of:

a. providing a tubular stent having an inner surface and an outersurface, said stent comprising an undulating wire having opposed firstand second ends and being helically wound into a plurality ofapproximate circumferential windings to define a stent wall; saidundulating wire having a plurality undulations defined by peaks andvalleys with peaks of adjacent approximate circumferential windingsbeing separated by a distance;

-   -   b. disposing a graft liner on said inner surface of said tubular        stent, said graft liner comprising first plurality of layers of        porous PTFE having no discernable node and fibril structure;    -   c. disposing a graft covering on said outer surface of said        tubular stent, said graft covering comprising a second plurality        of layers of porous PTFE having no discernable node and fibril        structure;    -   d. placing said tubular stent, graft liner and graft cover on a        shaped mandrel, said shaped mandrel including at least one crimp        shape on its outer surface; and    -   e. heating and sintering said tubular stent, graft liner and        graft cover so as to form a crimped stent graft comprising at        least one crimp conforming to the crimp shape of said shaped        mandrel.

Embodiment 15

An inflatable endovascular graft comprising:

-   -   a tubular graft having opposed first and second open ends and        having a first graft portion proximal to said first end and a        second graft portion proximal to said second end;    -   at least one circumferential inflatable channel disposed at said        first graft portion;    -   at least two circumferential inflatable channels disposed at        said second graft portion;    -   a longitudinal inflatable fill channel disposed between said        first end and said second end of said graft and in fluid        communication with said at least one circumferential inflatable        channel disposed at said first graft portion and said at least        two circumferential inflatable channels disposed at said second        graft portion; and    -   a first longitudinal inflatable channel disposed along said        second graft portion and traversing said at least two        circumferential inflatable channels disposed at said second        graft portion, wherein said first longitudinal inflatable        channel is in fluid communication with said at least two        circumferential inflatable channels disposed at said second        graft portion.

Embodiment 16

The inflatable endovascular graft of embodiment 15, wherein said firstlongitudinal inflatable channel comprises a plurality of channels.

Embodiment 17

The inflatable endovascular graft of embodiment 15, wherein said secondend is bifurcated.

Embodiment 18

The inflatable endovascular graft of embodiment 15, wherein second graftportion includes a circumference and at least one of said at least twocircumferential inflatable channels completely traverses saidcircumference of said second graft portion.

Embodiment 19

The inflatable endovascular graft of embodiment 15, wherein second graftportion includes a circumference and at least one of said at least twocircumferential inflatable channels partially traverses saidcircumference of said second graft portion.

Embodiment 20

A bifurcated inflatable endovascular graft comprising:

-   -   a tubular graft having a first end and an opposed second end,        said second end being a bifurcated end having a first branch and        a second branch, said first end having a first graft portion        proximal to said first end, said first branch having a first        branch portion proximal to said second end, said second branch        having a second branch portion proximal to said second end;    -   at least one circumferential inflatable channel disposed at said        first graft portion;    -   at least two circumferential inflatable channels disposed at        said first branch portion;    -   at least two circumferential inflatable channels disposed at        said second branch portion; a first longitudinal inflatable fill        channel disposed between said first end and said end of said        first branch portion, said first longitudinal inflatable fill        channel being in fluid communication with said at least one        circumferential inflatable channel disposed at said first graft        portion and said at least two circumferential inflatable        channels disposed at said first branch portion;    -   a second longitudinal inflatable fill channel disposed between        said first end and said end of said second branch portion, said        second longitudinal inflatable fill channel being in fluid        communication with said at least one circumferential inflatable        channel disposed at said first graft portion and said at least        two circumferential inflatable channels disposed at said second        branch portion; and    -   a first longitudinal inflatable channel disposed along said        first branch portion and traversing said at least two        circumferential inflatable channels disposed at said first        branch portion, wherein said first longitudinal inflatable        channel is in fluid communication with said at least two        circumferential inflatable channels disposed at said first        branch portion.

Embodiment 21

The bifurcated inflatable endovascular graft of embodiment 20, furthercomprising a second longitudinal inflatable channel disposed along saidsecond branch portion and traversing said at least two circumferentialinflatable channels disposed at said second branch portion, wherein saidsecond longitudinal inflatable channel is in fluid communication withsaid at least two circumferential inflatable channels disposed at saidsecond branch portion.

Embodiment 22

The bifurcated inflatable endovascular graft of embodiment 20, whereinsaid first branch portion includes a circumference and at least one ofsaid at least two circumferential inflatable channels at said firstbranch portion completely traverses said circumference of said firstbranch portion.

Embodiment 23

The bifurcated inflatable endovascular graft of embodiment 22, whereinone of said at least two circumferential inflatable channels at saidfirst branch is disposed at a location furthest from said first end, theone of at least two circumferential inflatable channels at said firstbranch disposed at a location furthest from said first end completelytraversing said circumference of said first branch portion.

Embodiment 24

The bifurcated inflatable endovascular graft of embodiment 20, whereinfirst branch portion includes a circumference and at least one of saidat least two circumferential inflatable channels at said first branchportion partially traverses said circumference of said first branchportion.

Embodiment 25

The bifurcated inflatable endovascular graft of embodiment 20, whereinsecond branch portion includes a circumference and at least one of saidat least two circumferential inflatable channels at said second branchportion completely traverses said circumference of said second branchportion.

Embodiment 26

The bifurcated inflatable endovascular graft of embodiment 25, whereinone of said at least two circumferential inflatable channels at saidsecond branch is disposed at a location furthest from said first end,the one of at least two circumferential inflatable channels at saidsecond branch disposed at a location furthest from said first endcompletely traversing said circumference of said second branch portion.

Embodiment 27

The bifurcated inflatable endovascular graft of embodiment 20, whereinsecond branch portion includes a circumference and at least one of saidat least two circumferential inflatable channels at said second branchportion partially traverses said circumference of said second branchportion.

Embodiment 28

A modular endovascular graft comprising:

-   -   a tubular graft having a first end and an opposed second end,        said second end being a bifurcated end having a first branch and        a second branch, said first end having a first graft portion        proximal to said first end, said first branch having a first        branch portion proximal to said second end, said second branch        having a second branch portion proximal to said second end;    -   at least one circumferential inflatable channel disposed at said        first graft portion;    -   at least two circumferential inflatable channels disposed at        said first branch portion;    -   at least two circumferential inflatable channels disposed at        said second branch portion; a first longitudinal inflatable fill        channel disposed between said first end and said end of said        first branch portion and in fluid communication with said at        least one circumferential inflatable channel disposed at said        first graft portion and said at least two circumferential        inflatable channels disposed at said first branch portion;    -   a second longitudinal inflatable fill channel disposed between        said first end and said end of said second branch portion and in        fluid communication with said at least one circumferential        inflatable channel disposed at said first graft portion and said        at least two circumferential inflatable channels disposed at        said second branch portion;    -   a first longitudinal inflatable channel dispose along said first        branch portion and traversing said at least two circumferential        inflatable channels disposed at said first branch portion,        wherein said first longitudinal inflatable channel is in fluid        communication with said at least two circumferential inflatable        channels disposed at said first branch portion;    -   a second longitudinal inflatable channel dispose along said        second branch portion and traversing said at least two        circumferential inflatable channels disposed at said second        branch portion, wherein said second longitudinal inflatable        channel is in fluid communication with said at least two        circumferential inflatable channels disposed at said second        branch portion.    -   a first stent-graft securable to said first branch portion; and    -   a second stent-graft securable to said second branch portion.

Embodiment 29

The modular graft of embodiment 28, wherein at least one of said firststent-graft and said second stent-graft comprises:

-   -   a tubular stent wall having opposed first and second ends;    -   an undulating wire having opposed first and second ends and        being helically wound into a plurality of approximate        circumferential windings to define said stent wall;    -   said undulating wire having a plurality undulations defined by        peaks and valleys;    -   wherein peaks of adjacent approximate circumferential windings        are separated by a distance, said distance between adjacent        peaks at said first end being different from said distance        between adjacent peaks at said second end.

Embodiment 30

The modular graft of embodiment 29, wherein said first wire end issecured to a first undulation at said first end and said second wire endis secured to a second undulation at said second end.

Embodiment 31

The modular graft of embodiment 29, further comprising:

-   -   a graft liner comprising first plurality of layers of porous        PTFE having no discernable node and fibril structure; and    -   a graft covering comprising a second plurality of layers of        porous PTFE having no discernable node and fibril structure;    -   wherein said tubular stent wall is securably disposed between        said graft covering and said graft lining.

Embodiment 32

The modular graft of embodiment 31, wherein said graft liner of said atleast one of said first stent-graft and said second stent-graft and saidgraft covering of said at least one of said first stent-graft and saidsecond stent-graft is crimped between said peaks of adjacent approximatecircumferential windings to provide crimped graft portions.

Embodiment 33

The modular graft of embodiment 32, wherein said crimped graft portionsare approximate circumferential crimped portions.

With regard to the above detailed description, like reference numeralsused therein refer to like elements that may have the same or similardimensions, materials and configurations. While particular forms ofembodiments have been illustrated and described, it will be apparentthat various modifications can be made without departing from the spiritand scope of the embodiments of the invention. Accordingly, it is notintended that the invention be limited by the forgoing detaileddescription.

What is claimed is:
 1. An endovascular stent-graft comprising: a graft;and an undulating wire connected to the graft, the undulating wirehelically wound in a length direction to form a plurality of undulatingwindings for a first portion, a second portion, and a third portionbetween the first and second portions in the length direction, each ofthe undulating windings having peaks and valleys, wherein each of theundulating windings have a peak height defined as a distance Y between apeak and an immediately adjacent valley of a corresponding undulatingwinding, wherein each immediately adjacent undulating windings areseparated from each other by a valley-to-peak distance defined as adistance X between a valley of one of the immediately adjacentundulating windings and a peak of the other immediately adjacentundulating windings, and wherein a ratio X/Y between the valley-to-peakdistance X and the peak height Y of the undulating windings of the thirdportion is greater than the ratio X/Y of the undulating windings of eachof the first and second portions.
 2. The endovascular stent-graft ofclaim 1, wherein the ratio X/Y of the undulating windings of the thirdportion is a positive value, and the ratio X/Y of the undulatingwindings for at least one of the first or second portions is a negativevalue.
 3. The endovascular stent-graft of claim 1, wherein the ratio X/Yof the undulating windings of the first portion is greater than theratio X/Y of the undulating windings of the second portion.
 4. Theendovascular stent-graft of claim 3, wherein the ratio X/Y of theundulating windings of the first portion is from about −0.1 to about0.3.
 5. The endovascular stent-graft of claim 1, wherein the graftcomprises a crimped region between at least one adjacent pair ofundulating windings.
 6. The endovascular stent-graft of claim 5, whereinthe crimped region comprises a crimp that extends in a radial directionalong a circumference of the graft.
 7. The endovascular stent-graft ofclaim 6, wherein the crimp extends entirely along the circumference ofthe graft.
 8. The endovascular stent graft of claim 6, wherein the crimpextends partially along the circumference of the graft.
 9. Theendovascular stent graft of claim 8, wherein the crimp has asemi-circular shape.
 10. The endovascular stent graft of claim 1,wherein the graft comprises a plurality of layers, and the undulatingwire is disposed between the layers of the graft.
 11. The endovascularstent graft of claim 1, wherein the second portion is configured toanchor the stent-graft in a main body graft, and the first portion isconfigured to anchor the stent-graft in an artery.
 12. A method ofmaking an endovascular stent-graft comprising: providing a graft;helically winding an undulating wire in a length direction to form aplurality of undulating windings for a first portion, a second portion,and a third portion between the first and second portions in the lengthdirection, each of the undulating windings having peaks and valleys,wherein the forming of the undulating windings comprises: disposing eachof the undulating windings to have a peak height defined as a distance Ybetween a peak and an immediately adjacent valley of a correspondingundulating winding; and separating each immediately adjacent undulatingwindings from each other by a valley-to-peak distance defined as adistance X between a valley of one of the immediately adjacentundulating windings and a peak of the other immediately adjacentundulating windings, wherein a ratio X/Y between the valley-to-peakdistance X and the peak height Y of the undulating windings of the thirdportion is greater than the ratio X/Y of the undulating windings of eachof the first and second portions; and connecting the undulating wire tothe graft.
 13. The method of claim 12, wherein the ratio X/Y of theundulating windings of the third portion is a positive value, and theratio X/Y of the undulating windings for at least one of the first orsecond portions is a negative value.
 14. method of claim 12, wherein theratio X/Y of the undulating windings of the first portion is greaterthan the ratio X/Y of the undulating windings of the second portion. 15.The method of claim 14, wherein the ratio X/Y of the undulating windingsof the first portion is from about −0.1 to about 0.3.
 16. The method ofclaim 12, further comprising forming a crimped region on the graftbetween at least one adjacent pair of undulating windings, wherein thecrimped region comprises at least one crimp.
 17. The method of claim 16,wherein the forming of the crimped region comprises: stretching theundulating wire; disposing one or more inner graft layers of the grafton an inner surface of the axially stretched undulating wire; disposingone or more outer graft layers of the graft on an outer surface of theaxially stretched undulating wire; and relaxing the undulating wire toform the at least one crimp.
 18. The method of claim 16, wherein theforming of the crimped region comprises: arranging the graft and thehelically wound undulating wire on a mandrel having at least one crimpshape on an outer surface of the mandrel; and heating the graft and thehelically wound undulating wire so that the at least one crimp is formedin the crimped region conforming to the at least one crimp shape of themandrel.
 19. The method of claim 16, wherein the crimped region extendsin a radial direction along a circumference of the graft.
 20. The methodof claim 12, wherein the graft comprises a plurality of layers, and theundulating wire is disposed between the layers of the graft.